# People v. McKnight

> Supreme Court of Colorado · May 20, 2019 · 446 P.3d 397

URL: https://www.frixlaw.com/law-library/cases/4398697

## Case

- **Full name:** The PEOPLE of the State of Colorado, Petitioner, v. Kevin Keith MCKNIGHT, Respondent.
- **Court:** Supreme Court of Colorado
- **Decided:** May 20, 2019
- **Citations:** 446 P.3d 397; 2019 CO 36
- **Precedential status:** Published
- **Opinion:** Opinion
- **Judges:** , Coats, Samour
- **Cited by:** 32 later opinions in the Frix Law Library

## Citator (automated)

- No negative treatment found by the automated citator. That is not the same as a confirmation that the case is good law; read the citing cases.
- Full citator and citing cases: https://www.frixlaw.com/law-library/cases/4398697

## How later opinions describe it (automated extraction)

- holding that a dog sniff is a search that must be supported by probable cause under Colorado law because “persons twenty-one or older may lawfully possess [cannabis] in small amounts” in Colorado and, thus, “a drug-detection dog that alerts to even the slightest amount of mari…
- reasoning that the legalization of marijuana under article XVIII, section 16 of the Colorado Constitution "expanded the protections of article II, section 7 to provide a reasonable expectation of privacy to engage in the lawful activity of possessing marijuana in Colorado"
- holding that after Colorado’s legalization of marijuana possession, the sniff is a search that must be supported by probable cause

## Opinion text

Opinions of the Colorado Supreme Court are available to the
public and can be accessed through the Judicial Branch’s homepage at
http://www.courts.state.co.us. Opinions are also posted on the
Colorado Bar Association’s homepage at http://www.cobar.org.

ADVANCE SHEET HEADNOTE
May 20, 2019

2019 CO 36

No. 17SC584, People v. McKnight—Searches and Seizures—Drug-Detection Dogs—
Probable Cause.

In this opinion, the supreme court considers the impact of the legalization of small

amounts of marijuana for adults who are at least twenty-one years old on law

enforcement’s use of drug-detection dogs that alert to marijuana when conducting an

exploratory sniff of an item or area.

The supreme court holds that a sniff from a drug-detection dog that is trained to

alert to marijuana constitutes a search under the Colorado Constitution because that sniff

can detect lawful activity, namely the legal possession of up to one ounce of marijuana

by adults twenty-one and older. The supreme court further holds that, in Colorado, law

enforcement officers must have probable cause to believe that an item or area contains a

drug in violation of state law before deploying a drug-detection dog that alerts to

marijuana for an exploratory sniff.

The supreme court concludes by determining that there was no probable cause in

this case to justify the sniff of the defendant’s truck by a drug-detection dog trained to

alert to marijuana, and thus, the trial court erred in denying the defendant’s motion to
suppress. The supreme court further concludes that the appropriate remedy for this

violation of the Colorado Constitution is the exclusion of the evidence at issue. Thus, the

supreme court affirms the court of appeals’ decision to reverse McKnight’s judgment of

conviction.
The Supreme Court of the State of Colorado
2 East 14th Avenue • Denver, Colorado 80203

2019 CO 36

Supreme Court Case No. 17SC584
Certiorari to the Colorado Court of Appeals
Court of Appeals Case No. 16CA50

Petitioner:

The People of the State of Colorado,

v.

Respondent:

Kevin Keith McKnight.

Judgment Affirmed
en banc
May 20, 2019

Attorneys for Petitioner:
Philip J. Weiser, Attorney General
Paul Koehler, First Assistant Attorney General
Denver, Colorado

Attorneys for Respondent:
Megan A. Ring, Public Defender
John Plimpton, Deputy Public Defender
Denver, Colorado

JUSTICE HOOD delivered the Opinion of the Court.
CHIEF JUSTICE COATS dissents, and JUSTICE BOATRIGHT and JUSTICE
SAMOUR join in the dissent.
JUSTICE SAMOUR dissents, and JUSTICE BOATRIGHT joins in the dissent.
¶1 Inside defendant Kevin McKnight’s truck, police officers discovered a pipe

containing what later proved to be methamphetamine residue. That discovery

culminated in McKnight’s conviction for certain drug offenses. On appeal, he challenged

the constitutionality of the search that revealed the pipe.

¶2 A division of the court of appeals reversed McKnight’s convictions. People v.

McKnight, 2017 COA 93, ¶ 25, __ P.3d __. Each member of the division wrote separately,

wrestling with what effect, if any, legalized marijuana in Colorado should have on the

constitutionality of the search of McKnight’s truck. To which you might say, but this is a

methamphetamine case. So, why are we talking about marijuana? Well, the drug-

detection dog used to find the pipe, Kilo, was trained to alert on multiple drugs, including

marijuana. Even a hint of marijuana can trigger the same response from Kilo as any

quantity of methamphetamine.

¶3 And that’s where things get tricky. After all, the possession of an ounce or less of

marijuana by someone twenty-one or older is legal in Colorado, following the passage of

Amendment 64, Colo. Const. art. XVIII, § 16(3), even though such possession remains

illegal under federal law. Thus, no matter how reliable his nose, Kilo can now render a

kind of false positive for marijuana. He has been trained to alert to marijuana based on

the notion that marijuana is always contraband, when that is no longer true under state

law. And historically, whether a drug-detection dog might alert on noncontraband

drives whether the dog’s sniff constitutes a search implicating constitutional protections.

The dog’s sniff arguably intrudes on a person’s reasonable expectation of privacy in

2
lawful activity. If so, that intrusion must be justified by some degree of particularized

suspicion of criminal activity.

¶4 Does this mean that Amendment 64 gave McKnight a reasonable expectation of

privacy under either the federal or state constitution that was violated by Kilo’s keen

sense of smell? McKnight says yes. Among other things, he claims that the Colorado

Constitution prohibited Kilo’s intrusion without at least reasonable suspicion that

McKnight had committed or was committing a crime. Because there was none, McKnight

asserts that the trial court should have suppressed the pipe. Two members of the division

agreed. McKnight, ¶ 3.

¶5 And even if the “sniff [was] up to snuff” (to use Justice Kagan’s popular shorthand

from a slightly different context in Florida v. Harris, 568 U.S. 237, 248 (2013)), McKnight

further argued that there was no probable cause for the post-sniff hand search of his truck

that revealed the pipe. Again, because of Amendment 64, two members of the division

agreed. McKnight, ¶ 4.

¶6 The People counter that, despite Amendment 64, marijuana remains contraband

in many circumstances at the state level, and illegal under all circumstances federally,

and thus Kilo’s sniff was not a search requiring so much as reasonable suspicion. The

People further contend that an alert from a dog trained to detect marijuana, in addition

to other substances, still provides probable cause justifying a search.

¶7 We hold that a sniff from a drug-detection dog that is trained to alert to marijuana

constitutes a search under article II, section 7 of the Colorado Constitution because that

sniff can detect lawful activity, namely the legal possession of up to one ounce of

3
marijuana by adults twenty-one and older. We further hold that, in Colorado, law

enforcement officers must have probable cause to believe that an item or area contains a

drug in violation of state law before deploying a drug-detection dog that alerts to

marijuana for an exploratory sniff. Because there was no such probable cause justifying

Kilo’s search of McKnight’s truck, the trial court erred in denying McKnight’s motion to

suppress.

¶8 Accordingly, we affirm the judgment of the court of appeals.

I. Facts and Procedural History

¶9 Evidence presented at a suppression hearing established the following facts.

¶10 While on patrol in an unmarked police vehicle one night in February 2015, Craig

Police Officer Bryan Gonzales observed a parked pickup truck facing the wrong way in

a one-way alley near an apartment complex. A man stood outside of the passenger-side

door of the truck. Although Officer Gonzales saw no behavior consistent with an

exchange or transaction, he followed the truck as it traveled a few blocks. The truck then

parked in front of a residence where police had found drugs almost two months earlier,

and it remained parked there for approximately fifteen minutes. During that time, no

one exited the truck or the residence. When the truck started moving again, Gonzales

trailed along.

¶11 When the driver of the truck failed to signal a turn, Gonzales pulled the truck over.

He discovered that McKnight was the driver. And Gonzales recognized the passenger

as someone who had used methamphetamine “at some point in the past,” but he wasn’t

sure how recently.

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¶12 During the traffic stop, Gonzales asked Sergeant Courtland Folks of the Moffat

County Sheriff’s Office to respond with his drug-detection dog, Kilo, who had been

trained to detect the odors of marijuana, methamphetamine, cocaine, heroin, and ecstasy.

If Kilo detects the scent of any one of those substances, he should alert. And he exhibits

the same alert for all five drugs.

¶13 Within five minutes of the stop, Kilo was on the job. As Folks walked Kilo around

McKnight’s truck, Folks asked McKnight if he had “any narcotics on him.” McKnight

said no. Kilo quickly “alerted” on the driver’s door beneath the driver’s open window.

This means that Kilo engaged in a rapid sniffing pattern and behaved in a manner

suggesting the presence of one of the substances on which he had been trained.

According to Folks, Kilo then “put his nose on the driver’s door, back to the door handle,

did a purge, which means he cleared his nose, took another deep breath and immediately

started giving a trained indication, which was barking.”

¶14 The officers then ordered McKnight and the passenger to exit the truck. After they

complied, the officers patted them down and found nothing on them. The officers then

searched the truck by hand. In a storage compartment under the rear seat, they found a

pipe containing suspected methamphetamine residue.

¶15 Before trial, the defense moved to suppress the pipe, arguing that it was the fruit

of an unconstitutional search. Specifically, McKnight argued that because marijuana is

legal in Colorado and Kilo was trained to detect marijuana, Kilo’s sniff was a search that

required particularized suspicion of criminal activity before Kilo could be deployed, and

there was no such suspicion on these facts. Moreover, he contended that Kilo’s alert did

5
not provide probable cause for a full-blown, human search of the truck. Through counsel,

McKnight grounded his arguments in the search and seizure clauses of both the United

States and Colorado Constitutions.

¶16 After a hearing, the trial court denied the motion to suppress. In relevant part, the

trial court noted that the possession of marijuana remains illegal under many

circumstances in Colorado and is categorically illegal under federal law. Without

explicitly stating as much, the trial court seemed to reason that a sniff by a dog trained to

detect marijuana does not constitute a search. And even if Kilo’s sniff was a search, the

trial court went on to conclude that there was reasonable suspicion of criminal activity

supporting the search. With ample record support, the court also concluded that Kilo

reliably sniffs out the drugs on which he’s been trained. The trial court did not address

whether there was probable cause for the officers’ hand search of the truck.

¶17 A jury later convicted McKnight of possession of a controlled substance and

possession of drug paraphernalia.

¶18 McKnight appealed. In three separate but partially overlapping opinions, the

court of appeals unanimously agreed that the trial court erred in denying McKnight’s

motion to suppress the pipe and that the error was not harmless. Therefore, the division

reversed McKnight’s convictions.

• Judge Dailey, writing for himself and Judge Berger, agreed with McKnight
that, under the Colorado Constitution after the enactment of Amendment 64,
Kilo’s sniff was a search requiring reasonable suspicion of criminal activity.
McKnight, ¶ 18 (“Because a dog sniff of a vehicle could infringe upon a
legitimate expectation of privacy solely under state law, that dog sniff should
now be considered a ‘search’ for purposes of article II section 7 of the state

6
constitution where the occupants are twenty-one years or older.”). Judge
Dailey further determined that the reasonable suspicion standard should
govern, and he concluded that the totality of the circumstances did not give
the police reasonable suspicion that McKnight had engaged in criminal
activity. Id. at ¶¶ 19–20, 22–24.

• Judge Jones, writing for himself and Judge Berger, agreed with McKnight that
Kilo’s alert, even in combination with other circumstances, did not give the
police probable cause to conduct a warrantless hand search of McKnight’s
truck. Id. at ¶¶ 49–54 (Jones, J., specially concurring). In doing so, Judge
Jones sidestepped the issue of whether Kilo’s sniff now constitutes a search
under state law. Id. at ¶ 37.

• Judge Berger, writing for himself, explained how a person could have an
enforceable expectation of privacy in the possession of marijuana under state
law, even in the face of a federal prohibition. First, he noted that Colorado
courts must give effect to Colorado voters’ enactment of Amendment 64. Id.
at ¶ 29 (Berger, J., specially concurring). Second, he observed that the People
have not argued that Amendment 64 is preempted by federal law. Id.
Finally, he concluded that when Amendment 64 legalized possession of up to
one ounce of marijuana for personal use by persons twenty-one years of age
or older, it also limited police authority to enforce the federal prohibition. Id.
at ¶ 31.

¶19 The People filed a petition for a writ of certiorari, and we agreed to review the

case.1

1 We granted certiorari on two issues:
1. Whether, given marijuana’s status as legal in some regards under state
law and illegal under federal law, marijuana is ‘contraband’ for the
purpose of a drug-detection dog’s sniff.
2. Whether an alert by a drug-detection dog that is trained to detect
marijuana and other controlled substances can supply probable cause to
justify a search.

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II. Analysis

¶20 After identifying the standard of review, we examine the parallel evolution of

federal and state jurisprudence concerning police use of drug-detection dogs. We review

long-standing law reasoning that a sniff is not a search because an individual has no

legitimate expectation of privacy as to contraband. But after the passage of Amendment

64, possession of an ounce or less of marijuana by someone twenty-one or older is legal,

and thus, marijuana is no longer always “contraband” under state law. Because Kilo’s

sniff could detect lawful activity, we conclude his sniff was a search under the Colorado

Constitution. We then consider what level of suspicion would justify deploying such a

dog to sniff a vehicle, ultimately concluding that, because the sniff is a search, there must

be probable cause to believe a vehicle contains illegal narcotics under state law before

deploying a drug-detection dog trained to alert to marijuana. We conclude that, under

the totality of the circumstances, there was no probable cause justifying the use of Kilo to

sniff McKnight’s truck or the subsequent hand search of the truck, and, exclusion of the

pipe is the appropriate remedy for this violation of the Colorado Constitution.

A. Standard of Review

¶21 When reviewing a suppression order, we defer to the trial court’s factual findings

if the record supports them, but we review de novo the court’s legal conclusions. Grassi

v. People, 2014 CO 12, ¶ 11, 320 P.3d 332, 335. So, we address the constitutionality of Kilo’s

sniff and the subsequent hand search of the truck de novo.

B. Federal Law Governing Searches and Drug-Detection Dogs

¶22 The Fourth Amendment to the United States Constitution states:

8
The right of the people to be secure in their persons, houses, papers, and
effects, against unreasonable searches and seizures, shall not be violated,
and no Warrants shall issue, but upon probable cause, supported by Oath
or affirmation, and particularly describing the place to be searched, and the
persons or things to be seized.

It “protects people, not places” from unreasonable governmental searches and seizures.

Katz v. United States, 389 U.S. 347, 351 (1967); see also U.S. Const. amend. IV. A search in

the constitutional sense occurs “when the government violates a subjective expectation

of privacy that society recognizes as reasonable.” Kyllo v. United States, 533 U.S. 27, 33

(2001) (citing Katz, 389 U.S. at 361 (Harlan, J., concurring)).

¶23 “Warrantless searches are presumptively unreasonable,” and thus

unconstitutional, unless an exception to the warrant requirement exists. United States v.

Karo, 468 U.S. 705, 717 (1984). Courts measure the constitutionality of a search (either

pursuant to a warrant or warrantless) at the time a search is performed. The Fourth

Amendment does not favor post hoc justifications based on what was found during a

search. See, e.g., People v. Sotelo, 2014 CO 74, 336 P.3d 188 (“[C]ourts may not use the

benefit of hindsight in evaluating application of the Fourth Amendment.”); see also

California v. Acevedo, 500 U.S. 565, 599 (1991) (Stevens, J., dissenting) (“Neither evidence

uncovered in the course of a search nor the scope of the search conducted can be used to

provide post hoc justification for a search unsupported by probable cause at its

inception.”); United States v. Montoya de Hernandez, 473 U.S. 531, 559 (1985) (Brennan, J.,

dissenting) (“[P]ost hoc rationalizations have no place in our Fourth Amendment

jurisprudence, which demands that we ‘prevent hindsight from coloring the evaluation

9
of the reasonableness of a search or seizure.’” (quoting United States v. Martinez-Fuerta,

428 U.S. 543, 565 (1976))).

¶24 A warrantless search may be constitutional if there was probable cause to believe

the place or item to be searched contained contraband or evidence of a crime, and the

circumstances met an exception to the warrant requirement. One such exception is the

automobile exception. Beginning with Carroll v. United States, the Supreme Court has

reasoned that automobiles warrant a lesser degree of privacy than that afforded to homes

because of a vehicle’s “ready” mobility, the existing, pervasive government regulation of

cars, and the low probability that a car is used to store personal effects. See 267 U.S. 132,

153 (1925) (reasoning that there is “a necessary difference between a search of a store,

dwelling house, or other structure . . . [where] a proper official warrant readily may be

obtained and a search of a ship, motor boat, wagon, or automobile . . . where it is not

practicable to secure a warrant, because the vehicle can be quickly moved”). Nearly a

century later, the law remains the same: If an officer has lawfully stopped a vehicle, and

has probable cause to believe the vehicle contains evidence of a crime, then the officer

may conduct a search of the car without first obtaining a warrant. Collins v. Virginia, 138

S. Ct. 1663, 1670 (2018).

¶25 As the Supreme Court continued to embrace and refine the automobile exception,

drug-detection dogs scampered on to the scene. United States v. Place marked the

Supreme Court’s first foray into this area of the law. 462 U.S. 696 (1983). In Place, two

law enforcement officers grew suspicious that Place might be carrying narcotics after

observing him at Miami International Airport. Id. at 698. The officers remained

10
suspicious after talking with the defendant, though they ultimately decided not to search

his luggage. Id. The officers looked closely at the luggage tags on the defendant’s

checked bags and noticed discrepancies between the two addresses and the phone

number the defendant gave the airline. Id. The officers notified law enforcement agents

in New York of the defendant’s impending arrival. Id. Two Drug Enforcement

Administration agents contacted the defendant when he landed, informed the defendant

that they believed he may be transporting illegal narcotics, and ultimately seized his

luggage in order to subject it to a sniff from a drug-detection dog. Id. at 698–99.

¶26 Though Place turned on whether the seizure of the defendant’s luggage without

probable cause violated the Fourth Amendment, the Court discussed the use of

drug-detection dogs at airports to sniff luggage suspected of containing illegal narcotics.

See id. at 707. The Court reasoned that exposing “temporarily detain[ed] personal

luggage” to a dog trained to detect narcotics wasn’t a search under the Fourth

Amendment. Id. at 697–98. The sniff is “sui generis,” stated the Court, because it is less

intrusive than other search techniques and it can only reveal the “presence or absence of

narcotics, a contraband item.” Id. at 707. The Court’s rationale thus hinged on two

notions: (1) A dog sniff is a minimally intrusive tactic (2) that can only reveal whether or

not contraband is present in the luggage. Beyond that, the sniff reveals nothing. Despite

the narrow circumstances in which the Court made these statements, they have formed

the foundation for much federal (and state) jurisprudence on dog sniffs.

¶27 The Supreme Court relied on this reasoning in Illinois v. Caballes to conclude that

“the use of a well-trained narcotics-detection dog—one that ‘does not expose

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noncontraband items that otherwise would remain hidden from public view’—during a

lawful traffic stop, generally does not implicate legitimate privacy interests.” 543 U.S.

405, 409 (2005) (internal citation omitted) (quoting Place, 462 U.S. at 707). In Caballes, an

officer led a drug-detection dog around a vehicle that was lawfully stopped for speeding.

Id. at 406. The dog alerted at the trunk, leading to a search that revealed marijuana. Id.

Looking back to Place, the Court rejected the claim that the dog sniff was unconstitutional

because there was no reasonable suspicion that the defendant possessed narcotics when

he was initially stopped. Id. at 408–09. Notably, the Court didn’t focus on how the

officers in Place had already grown suspicious that the defendant was engaged in illegal

narcotics activity before stopping and contacting the defendant. Compare id., with Place,

462 U.S. at 698–700. Instead, the Court reasoned that reasonable suspicion wasn’t

necessary to justify the dog sniff because it could only detect contraband, and “any

interest in possessing contraband cannot be deemed ‘legitimate,’ . . . thus, governmental

conduct that only reveals the possession of contraband ‘compromises no legitimate

privacy interest.’” Id. at 408 (quoting United States v. Jacobsen, 466 U.S. 109, 123 (1984)).2

2There are other limitations on the use of drug-detection dogs not at issue here. First, the
dog and its handler must be in a place where they have a right to be. Florida v. Jardines,
569 U.S. 1, 8–9 (2013). Second, the use of a drug-detection dog during a traffic stop may
not impermissibly prolong the stop. Rodriguez v. United States, 135 S. Ct. 1609, 1612 (2015).
McKnight does not assert that the police violated either of these limitations.
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C. Colorado Law: Pre-Amendment 64

¶28 Our search and seizure jurisprudence took a different path. In decades past, our

opinions demonstrated a willingness to interpret the state constitution to afford broader

protections than its federal counterpart. Yet, in recent years, we have moved away from

this interpretive independence.

¶29 Article II, section 7 of the Colorado Constitution states:

The people shall be secure in their persons, papers, homes and effects, from
unreasonable searches and seizures; and no warrant to search any place or
seize any person or things shall issue without describing the place to be
searched, or the person or thing to be seized, as near as may be, nor without
probable cause, supported by oath or affirmation reduced to writing.

¶30 In Charnes v. DiGiacomo, this court first charted its own course in interpreting

article II, section 7 to afford broader protections than the Fourth Amendment. 612 P.2d

1117 (Colo. 1980). Charnes concerned a taxpayer’s challenge to a subpoena issued to his

bank by the Colorado Department of Revenue seeking the taxpayer’s financial records.

Id. at 1119. Applying United States v. Miller, this court concluded that the Fourth

Amendment did not shield the taxpayer’s financial records from government seizure

because the taxpayer could not claim any expectation of privacy in the information he

shared with his bank through financial transactions. Id. at 1120 (citing 425 U.S. 435

(1976)). But, the analysis did not end there. We then looked to article II, section 7 and

concluded that the analytical framework announced in Katz—whether the defendant had

a subjective expectation of privacy in his bank records that society was prepared to

recognize as reasonable—was also the framework to be applied under the Colorado

Constitution. See id. at 1120–21. Noting that Miller “does not determine the scope of

13
protection provided to individuals in Colorado by the constitution of this state,” we

concluded that, under the Colorado Constitution, bank depositors have a reasonable

expectation of privacy in records concerning their financial transactions held at banks in

Colorado. Id. Charnes was only the first in a series of cases holding that article II, section

7 provides greater privacy protections than the Fourth Amendment. See, e.g., People v.

Sporleder, 666 P.2d 135, 143–44 (Colo. 1983) (rejecting the U.S. Supreme Court’s reasoning

in Smith v. Maryland, 442 U.S. 735 (1979), to hold that the installation and use of a pen

register constitutes a search under state law); People v. Corr, 682 P.2d 20, 27–28 (Colo. 1984)

(applying the reasoning of Sporleder to conclude that a warrant is required to obtain

telephone toll records); People v. Oates, 698 P.2d 811, 815–16 (Colo. 1985) (rejecting the

reasoning of Karo, 468 U.S. 705, and holding that the installation and presence of a

tracking device in purchased commercial goods constitutes a search under the Colorado

Constitution).

¶31 In People v. Unruh, we considered the constitutional permissibility of a dog sniff of

a locked safe. 713 P.2d 370, 378–79 (Colo. 1986), abrogated by People v. Esparza, 2012 CO

22, 272 P.3d 367. We concluded that, despite the less intrusive nature of a dog sniff, it

was a search because the defendant had a reasonable expectation of privacy in the locked

safe. Id. In coming to this conclusion, we distinguished Place, noting that the sniff of a

person’s luggage at an airport was not deemed a search because the person has “no

reasonable expectation of privacy from an investigative technique as non-intrusive as a

dog sniff” at the airport. Id. at 378. We then had to decide whether a warrant was

necessary to deploy the drug-detection dog, or whether “something less than probable

14
cause” could justify the sniff. Id. We looked to Terry v. Ohio, 392 U.S. 1, 30–31 (1968),

where the U.S. Supreme Court held that an officer may conduct a stop if he has reasonable

suspicion criminal activity is occurring. We analogized an exploratory dog sniff to the

brief investigatory stops at issue in Terry, and we concluded that the proper “balance

between governmental and individual interests in this case” necessitated that there be

reasonable suspicion to justify the exploratory sniff. Unruh, 713 P.2d at 379. Our

reasoning rested primarily on two principles: (1) the defendant had a reasonable

expectation of privacy in the item searched (his locked safe), and (2) a dog sniff, though

a search, was a less intrusive search than a traditional search by hand. Id. at 377–79.

¶32 In People v. Haley, we applied the reasoning of Unruh to conclude that a dog sniff

resulting from an impermissibly prolonged traffic stop violated the protections of article

II, section 7.3 41 P.3d 666, 673–74, 676–77 (Colo. 2001), abrogated by Esparza, 2012 CO 22,

272 P.3d 367. This was so because the defendants had “a privacy interest in their persons

and vehicle being free from unreasonable governmental intrusion, and the drug

investigation following the traffic stop in this case required reasonable suspicion for the

dog sniff search to proceed.” Id. at 674. We acknowledged that “automobiles enjoy a

lesser expectation of privacy in our society than private homes,” but we also noted that

“citizens have a reasonable expectation of privacy from search and seizure in their cars

and in their persons as they travel the state’s roads.” Id. at 672 (citing New York v. Class,

3 The U.S. Supreme Court later reached a similar holding in Rodriguez, 135 S. Ct. at 1612.

15
475 U.S. 106, 112 (1986) (“A citizen does not surrender all the protections of the Fourth

Amendment by entering an automobile.”)).

¶33 However, in People v. Esparza, we reviewed our prior precedent on dog sniffs and,

in doing so, narrowed its scope. 2012 CO 22, 272 P.3d 367. We concluded that, “[d]espite

our broad language purporting to address dog sniffs in general,” our earlier decisions

suggested a “more limited rule” was appropriate. Id. at ¶ 9, 272 P.3d at 369. Specifically,

we noted that our dog-sniff jurisprudence has “been concerned with the nature of the

particular container being pursued and any official conduct making it possible for a

trained drug dog to sniff the container in the first place.” Id. at ¶ 8, 272 P.3d at 369.

Ultimately, we held “that an interest in possessing contraband cannot be deemed

legitimate under the state constitution any more than under the federal constitution, and

that official conduct failing to compromise any legitimate interest in privacy cannot be

deemed a search under the state constitution any more than under the federal

constitution.” Id. at ¶ 2, 272 P.3d at 368. Like the U.S. Supreme Court, we based our

holding in part on the purportedly binary nature of the dog’s sniff. The sniff, we

reasoned, could only communicate either the presence or absence of contraband. Id. at

¶ 11, 272 P.3d at 370.

¶34 Esparza thus represented a kind of return to the federal fold. The state of the law

was thus: (1) under the automobile exception, an officer may search a car without a

warrant if that officer has probable cause to believe there is contraband in the car; (2) an

officer doesn’t need reasonable suspicion to walk a drug-detection dog around a lawfully

stopped vehicle because the alert indicates only the presence of contraband, and people

16
do not have a legitimate expectation of privacy in contraband; and (3) an alert from a

drug-detection dog could provide probable cause for a subsequent hand search of the

car. See id. at ¶¶ 10–12, 272 P.3d at 370; see also People v. Mason, 2013 CO 32, ¶ 10, 310 P.3d

1003, 1005 (“It is now settled that walking a trained narcotics detection dog around a car

that has not been unlawfully stopped or detained does not implicate the protections of

either the Fourth Amendment or Article II, section 7 of the state constitution.”). And so

it has been for the better part of a decade.

D. Colorado Law: Post-Amendment 64

¶35 Has the passage of Amendment 64 altered this settled terrain? We began to

explore this question in our recent decisions in People v. Zuniga, 2016 CO 52, 372 P.3d

1052, and People v. Cox, 2017 CO 8, 401 P.3d 509. In both Zuniga and Cox, we found

probable cause supporting an automobile search based on a confluence of factors,

including the positive alert of a drug-detection dog that was trained to alert to marijuana.

Yet, in Zuniga, we concluded that the alert was legally ambiguous because a

drug-detection dog can’t distinguish legal marijuana from illegal marijuana, or legal

marijuana from illegal narcotics. See ¶¶ 18–23, 372 P.3d at 1057–59. Despite this

ambiguity, we held that the alert was still relevant to the overall probable cause analysis.

Id. Likewise in Cox, we concluded that the positive alert of a drug-detection dog was one

factor, among many, supporting a finding of probable cause to search a stopped vehicle.

¶ 17, 401 P.3d at 512–13.

¶36 In both Zuniga and Cox, we declined to address (1) whether the sniff of a dog

trained to detect marijuana was a search, and (2) whether a positive alert from a dog

17
trained to detect marijuana alone could establish probable cause. Significantly however,

these two recent decisions suggest the answer to the latter question is no. We

acknowledged that, with the legalization of small amounts of marijuana, a dog’s alert

doesn’t provide a yes-or-no answer to the question of whether illegal narcotics are

present in a vehicle. At most, the alert could be “suggestive of criminality,” but not

determinative on its own. See Zuniga, ¶ 23, 372 P.3d at 1059. Had the alert alone sufficed,

there would have been no need to evaluate other circumstances in either Zuniga or Cox.

Yet, we did just that. Thus, in finding that an alert from a drug-detection dog trained to

find marijuana is ambiguous, Zuniga and Cox represent a tentative step away from the

federal approach. See, e.g., Harris, 568 U.S. at 240, 247–48 (concluding that an alert from

a well-trained, reliable drug-detection dog could supply probable cause to search a

vehicle).

¶37 To be sure, marijuana remains illegal under federal law. The Federal Controlled

Substances Act prohibits the possession of marijuana for nearly all uses. 21 U.S.C.

§ 812(c)(10) (2012); 21 U.S.C. § 812(b)(1)(A)–(C) (2012); 21 U.S.C. § 844(a) (2012). “There

is no exception for marijuana use for medical purposes, nor is there an exception for use

in compliance with state law.” People v. Crouse, 2017 CO 5, ¶ 11, 388 P.3d 39, 42 (citing

Gonzales v. Raich, 545 U.S. 1, 14 (2005)). Consequently, marijuana remains contraband

under federal law and, arguably, Kilo’s sniff was not a search under the U.S. Supreme

18
Court’s interpretation of the Fourth Amendment in Caballes.4 See McKnight, ¶ 18 n.4.

This, however, leaves unanswered the question of whether Kilo’s sniff was nonetheless a

search under the corresponding provisions of our state constitution.5

¶38 We have opined that, despite the substantial similarity between article II, section

7 and the Fourth Amendment, “we are not bound by the United States Supreme Court’s

interpretation of the Fourth Amendment when determining the scope of state

constitutional protections.” Sporleder, 666 P.2d at 140. “There is no reason to think, as an

interpretive matter, that constitutional guarantees of independent sovereigns, even

guarantees with the same or similar words, must be construed in the same way.” Jeffrey

S. Sutton, 51 Imperfect Solutions: States and the Making of American Constitutional Law

4 Caballes, however, did not address the effect of a state law legalizing marijuana on the
question of whether a resident of the state would have a legitimate expectation of privacy
in lawful possession of marijuana.
5The People argue that, because marijuana remains federal contraband, we don’t need to
alter our dog-sniff jurisprudence. The People further suggest that, because of marijuana’s
contraband status under federal law, an alert from a drug-detection dog trained on
marijuana still supplies probable cause to believe illegal narcotics are present despite
Amendment 64. Yet, conspicuously absent from the People’s appeal to federal law is an
argument that Amendment 64 is preempted by federal law. See McKnight, ¶ 17 n.3
(opinion of Dailey, J.) (“No question has been raised in this case about whether
Amendment 64 is preempted by federal law.”); McKnight, ¶ 29 (Berger, J., specially
concurring) (“The Attorney General does not contend that Amendment 64 is displaced
by the Supremacy Clause of the Federal Constitution.”). The People cannot contend that
marijuana’s status as illegal under federal law controls our state law analysis while
simultaneously avoiding preemption. Because the People declined to address
preemption, we refrain as well. Cf. Greenlaw v. United States, 554 U.S. 237, 243 (2008)
(“[W]e rely on the parties to frame the issues for decision and assign to courts the role of
neutral arbiter of matters the parties present.”).

19
174 (2018); see also Thompson v. Dallas City Attorney’s Office, 913 F.3d 464, 471 (5th Cir. 2019)

(“Our Nation boasts not one Constitution but 51, meaning American constitutionalism

concerns far more than what began in Philadelphia 232 years ago.” (citing Sutton, supra)).

Indeed, the U.S. Supreme Court has a long tradition of encouraging us to scrutinize our

own state constitutional texts, declaring: “It is fundamental that state courts be left free

and unfettered by us in interpreting their state constitutions.” Minnesota v. Nat’l Tea Co.,

309 U.S. 551, 557 (1940); see also Cooper v. California, 386 U.S. 58, 62 (1967) (“Our holding,

of course, does not affect the State’s power to impose higher standards on searches and

seizures than required by the Federal Constitution if it chooses to do so.”); Massachusetts

v. Upton, 466 U.S. 727, 739 (1984) (Stevens, J., concurring) (“The States in our federal

system . . . remain the primary guardian of the liberty of the people.”); California v.

Greenwood, 486 U.S. 35, 43 (1988) (“Individual States may surely construe their own

constitutions as imposing more stringent constraints on police conduct than does the

Federal Constitution.”). Thus, state courts need not interpret state constitutional

provisions “as mere mirrors of federal protections.” Developments in the Law—The

Interpretation of State Constitutional Rights, 95 Harv. L. Rev. 1324, 1356 (1982); see also

William J. Brennan, Jr., State Constitutions and the Protection of Individual Rights, 90 Harv.

L. Rev. 489, 491 (1977) (“State constitutions, too, are a font of individual liberties, their

protections often extending beyond those required by the Supreme Court’s interpretation

of federal law.”).

¶39 And, because the protections afforded by both article II, section 7 and the Fourth

Amendment are “highly generalized,” we discern no reason to reflexively assume that

20
there must be “just one meaning over a range of differently situated sovereigns.” Sutton,

supra, at 174. Criminal law has traditionally been considered best left to the expertise of

the state courts as the vast majority of criminal prosecutions take place in state, rather

than federal, court. See Shirley S. Abrahamson, Criminal Law and State Constitutions: The

Emergence of State Constitutional Law, 63 Tex. L. Rev. 1141, 1150 (1985) (“Criminal law is

an area of traditional concern for state judges. It is an area of law in which state judges

have special experience and expertise.”); see also Tafflin v. Levitt, 493 U.S. 455, 465 (1990)

(reasoning, in part, that state courts can exercise concurrent jurisdiction over civil RICO

cases because these cases “involve asserted violations of state law . . . over which state

courts presumably have greater expertise”).

¶40 Moreover, we are confronted with a local development that further suggests

resolution under our state constitution is proper. “State courts . . . have a freer hand in

doing something the Supreme Court cannot: allowing local conditions and traditions to

affect their interpretation of a constitutional guarantee and the remedies imposed to

implement that guarantee.” Sutton, supra, at 17. When there are “general institutional

differences between the state government and its federal counterpart” or “distinctive

state-specific factors,” including the existence of state constitutional provisions that

provide rights not guaranteed by the federal constitution, interpreting the state

constitution in a manner that departs from federal courts’ interpretations of similar

federal provisions not only makes sense, it may be the most logical option. See

Developments in the Law, supra, at 1359–60.

21
¶41 Here, we have a state constitutional right not guaranteed by the federal

constitution. Amendment 64 provides that it is “not unlawful and shall not be an offense

under Colorado law” for a person who is at least twenty-one years of age to possess one

ounce or less of marijuana. Colo. Const. art. XVIII, § 16(3); see also Zuniga, ¶ 18, 372 P.3d

at 1057. Amendment 64 was enacted through the initiative process in 2012, and its

passage represents voters’ intent to legalize marijuana use, possession, and growth under

certain circumstances. Colo. Const. art. XVIII, § 16(1)(a) (designating the purpose of

Amendment 64 as “the people of the state of Colorado find and declare that the use of

marijuana should be legal for persons twenty-one years of age or older and taxed in a

manner similar to alcohol”). “Our goal in interpreting a citizen initiative is to ‘give effect

to the electorate’s intent.’” People v. Lente, 2017 CO 74, ¶ 16, 406 P.3d 829, 832 (quoting

Colo. Ethics Watch v. Senate Majority Fund, LLC, 2012 CO 12, ¶ 20, 269 P.3d 1248, 1253); see

also Commonwealth v. Craan, 13 N.E.3d 569, 577–78 (Mass. 2014) (discussing the

importance of implementing the people’s intent when examining the impact of a citizen

initiative decriminalizing possession of small amounts of marijuana under state law on

the probable cause analysis). Tellingly, Amendment 64 did more than just legalize

personal marijuana use, possession, and growth. The initiative also created a marijuana

industry. See Colo. Const. art. XVIII, § 16(4). And, Amendment 64 reflects a desire to

protect “individual privacy” by specifying that the Department of Revenue “shall not

require” individual consumers to provide any information beyond a government-issued

form of ID for age verification when purchasing marijuana at a retail marijuana store. Id.

§ 16(5)(c).

22
¶42 Marijuana is not only decriminalized in Colorado, it is legalized, regulated, and

taxed. Marijuana is now treated like guns, alcohol, and tobacco—while possession of

these items is lawful under some circumstances, it remains unlawful under others. See,

e.g., § 18-12-103, C.R.S. (2018) (making it unlawful to knowingly possess a firearm without

its serial number or other identifying mark); § 18-13-122(3)(a), C.R.S. (2018) (making it

unlawful for persons under twenty-one to possess or consume alcohol); § 18-13-121,

C.R.S. (2018) (making it unlawful to sell tobacco products to persons under eighteen).

Although possession of guns, alcohol, and tobacco can be unlawful, persons still maintain

an expectation of privacy in lawfully using or consuming those items. The same now

goes for marijuana: In legalizing marijuana for adults twenty-one and older, Amendment

64 expanded the protections of article II, section 7 to provide a reasonable expectation of

privacy to engage in the lawful activity of possessing marijuana in Colorado.

¶43 So, the rationale underlying Esparza no longer holds true when applied to Kilo’s

formidable nose. Because persons twenty-one or older may lawfully possess marijuana

in small amounts, a drug-detection dog that alerts to even the slightest amount of

marijuana can no longer be said to detect “only” contraband. Thus, an exploratory sniff

of a car from a dog trained to alert to a substance that may be lawfully possessed violates

a person’s reasonable expectation of privacy in lawfully possessing that item. Because

there was no way to know whether Kilo was alerting to lawful marijuana or unlawful

contraband, Kilo’s sniff violated McKnight’s reasonable expectation of privacy.

Therefore, under state law, Kilo’s sniff was a search that had to be constitutionally

justified.

23
¶44 Kilo’s sniff now seems more akin to the “sense-enhancing” technology at issue in

Kyllo. See 533 U.S. at 30. There, the U.S. Supreme Court held that the use of a

thermal-imaging device that was not used by the general public was a search because it

could reveal private, lawful activity occurring inside of a home. Id. at 40. With the device,

law enforcement could “explore details . . . that would previously have been unknowable

without physical intrusion.” Id. Though the U.S. Supreme Court focused its holding in

part on the fact that the device was used on the home, Kyllo’s central rationale is

instructive because “citizens [still] have a reasonable expectation of privacy from search

and seizure in their cars and in their persons as they travel the state’s roads.” Haley, 41

P.3d at 672; accord Caballes, 543 U.S. at 413 n.3 (Souter, J., dissenting) (“Any difference

between the dwelling in Kyllo and the trunk of the car . . . may go to the issue of the

reasonableness of the respective searches, but it has no bearing on the question of search

or no search. . . . The justifications required by the Fourth Amendment may or may not

differ as between the two practices, but if constitutional scrutiny is in order for the imager,

it is in order for the dog.”).

¶45 One might be tempted to underestimate the privacy interests at stake here.

Consider how the Kyllo Court emphasized that a thermal imager could reveal “intimate

details” of the home in reaching its conclusion that the use of the imager constituted a

search. 533 U.S. at 38. In contrast, in Dow Chemical Co. v. United States, the Court reasoned

in part that aerial photographs of an industrial complex didn’t violate the Fourth

Amendment because the photos were “not so revealing of intimate details” and

commercial property enjoys a lesser degree of privacy than the home. 476 U.S. 227,

24
237–38 (1986). As the Court stated, “[t]he intimate activities associated with family

privacy and the home and its curtilage simply do not reach the outdoor areas or spaces

between structures and buildings of a manufacturing plant.” Id. at 236. Though

automobiles have traditionally been accorded lesser protections than homes, a person

surely engages in more “intimate activities” in the solitary confines of his car as compared

to the “outdoor areas or spaces between buildings of a manufacturing plant.” Id. Such

intimate activities may include lawful transportation of an ounce or less of marijuana to

treat symptoms of a chronic illness, mitigate mental health conditions, or engage in

recreational activities that, while legal, one would just as soon not have disclosed to the

public. See Leg. Council Colo. Gen. Ass., Research Publ’n No. 475-0, An Analysis of the

2000 Statewide Ballot Proposals 2 (2000); Leg. Council Colo. Gen. Ass., Research Publ’n

No. 614, 2012 State Ballot Information Booklet 12 (2012). And Kilo’s extraordinarily

powerful nose can uncover this lawful activity. Though the sniff wouldn’t necessarily

result in the disclosure of why a person is carrying lawful amounts of marijuana, a person

may still reasonably expect that his decision to engage in lawful activity for such personal

reasons to remain private from others, including from a police officer and his canine.

¶46 We certainly aren’t the first to notice the similarities between a well-trained

drug-detection dog and other forms of investigative, sense-enhancing technologies that

can reveal private, lawful activity. See, e.g., Unruh, 713 P.2d at 376–77 (discussing the

rationale of a minority of courts that concluded a sniff was a search). As the concurrence

observed in United States v. Bronstein:

25
There is no legally significant difference between the use of an X-ray
machine or magnetometer to invade a closed area in order to detect the
presence of a metal pistol or knife, which we have held to be a search, and
the use of a dog to sniff for marijuana inside a private bag. Each is a non-
human means of detecting the contents of a closed area without physically
entering into it. . . . Neither constitutes a particularly offensive intrusion,
such as ransacking the contents of the hidden space, or exposing a person
to indignities in the case of a personal search. But the fact remains that each
detects hidden objects without actual entry and without the enhancement
of human senses. The fact that the canine’s search is more particularized
and discriminate than that of the magnetometer is not a basis for a legal
distinction. The important factor is not the relative accuracy of the sensing
device but the fact of the intrusion into a closed area otherwise hidden from
human view, which is the hallmark of any search.

521 F.2d 459, 464 (2d Cir. 1975) (Mansfield, J., concurring) (citation omitted); see also

Caballes, 543 U.S. at 413 (Souter, J., dissenting) (“[T]he sniff is the first step in a process

that may disclose ‘intimate details’ without revealing contraband, just as a

thermal-imaging device might do, as described in Kyllo v. United States.”). And Kilo’s

sniff isn’t all that different from the magnetometer or the thermal-imaging device. Kilo

has spent countless hours being trained to detect marijuana—he can even alert to

substances placed in a closed box and further sealed off with duct tape. Cf. Katz, 389 U.S.

at 361–62 (Harlan, J., concurring) (discussing how the defendant exhibited a subjective

expectation of privacy in his phone calls by entering a phone booth and shutting the door

behind him, and how that expectation was reasonable). “[Drug-detection dogs] are to

the poodle down the street as high-powered binoculars are to a piece of plain glass. Like

the binoculars, a drug-detection dog is a specialized device for discovering objects not in

plain view (or plain smell).” Jardines, 569 U.S. at 13 (Kagan, J., concurring).

26
¶47 Admittedly, many federal courts have come to a different conclusion on whether

a sniff of the exterior of a vehicle, or the air surrounding an item, constitutes a search.

These courts have reasoned that a person doesn’t have a legitimate expectation of privacy

under the Fourth Amendment in the odorous molecules that emanate from his car into

the open and public airspace. See, e.g., United States v. Morales-Zamora, 914 F.2d 200, 205

(10th Cir. 1990); United States v. Broadway, 580 F. Supp. 2d 1179, 1191 (D. Colo. 2008).

However, in those cases, the “odorous molecules” that a drug-detection dog could alert

to all belonged to what was clearly contraband—that isn’t true anymore in Colorado,

where some odorous molecules may be those emanating from lawfully possessed

marijuana.6 In short, none of these cases is on point because none involved legalized

marijuana. And that is precisely why we rest our holding on the Colorado Constitution,

not on the Fourth Amendment. To the extent we end up alone on a jurisprudential island,

it is an island on which Colorado voters have deposited us. Our role is not to question

their decision. Rather, it is to apply the logic of existing law to a changing world. Though

6 Other cases are further distinguishable because the item sniffed was in some public
space, such as at an airport, United States v. Goldstein, 635 F.2d 356, 358–59 (5th Cir. 1981),
or on a bus, United States v. Gant, 112 F.3d 239, 240–41 (6th Cir. 1997), or other area where
people cannot reasonably expect to have the same level of privacy as in a motor vehicle.
And, in some cases, the officers already had “considerable information” that an
individual was engaged in illegal narcotics activity before deploying the drug-detection
dog, United States v. Cruz, 1:07-cr-145-WSD, 2008 WL 11383985, *2 (N.D. Ga. May 15,
2008); in others, the defendant consented to a hand search of the vehicle that began before
a dog was even deployed, United States v. Corrujedo, No: 5:17-CR-24-RWS-CMC, 2017 WL
8809641, at *18 (E.D. Tex. Dec. 22, 2017).

27
we are the first court to opine on whether the sniff of a dog trained to detect marijuana in

addition to other substances is a search under a state constitution in a state that has

legalized marijuana, we probably won’t be the last. Since Amendment 64’s passage in

2012, nine other states and the District of Columbia have legalized possession of

small amounts of marijuana. Marijuana Overview, Nat’l Conference of State Legislatures

(Dec. 14, 2018), http://www.ncsl.org/research/civil-and-criminal-justice/marijuana-

overview.aspx [https://perma.cc/HMN2-PX38].

¶48 Because a sniff from a dog trained to detect marijuana (in addition to other

substances) can reveal lawful activity, we conclude that sniff is a search under article II,

section 7 and must be justified by some degree of suspicion of criminal activity.

E. Probable Cause Was Necessary for Kilo’s Search

¶49 Because we have concluded that the sniff from a dog trained to detect marijuana

is a search under article II, section 7, it follows that the search must be justified by

probable cause. However, as we are the first court to consider the impact of marijuana

legalization on a sniff from a dog trained to alert to even a hint of marijuana, we consider

whether reasonable suspicion would suffice, as the division below concluded after

reviewing our pre-Esparza caselaw, or if the intrusion warrants justification under the

usual probable cause standard.

¶50 “There is no more basic constitutional rule . . . than that which makes a warrantless

search unreasonable except in a few ‘jealously and carefully drawn’ exceptional

circumstances.” United States v. Watson, 423 U.S. 411, 427 (1976) (quoting Jones v. United

States, 357 U.S. 493, 499 (1958)). Because warrantless searches are presumptively

28
unreasonable, they must be supported by at least probable cause and justified under at

least one of these “carefully drawn” exceptions. Id.; see also Chambers v. Maroney, 399 U.S.

42, 51 (1970) (“In enforcing the Fourth Amendment’s prohibition against unreasonable

searches and seizures, the Court has insisted upon probable cause as a minimum

requirement for a reasonable search permitted by the Constitution.”). These two bedrock

principles apply just as forcefully to the protections promised by article II, section 7. See

Sporleder, 666 P.2d at 144 (“In the absence of some narrowly defined exception to the

warrant requirement . . . a warrantless search is presumed to be invalid.”); Mendez v.

People, 986 P.2d 275, 279 (Colo. 1999) (“[A] warrantless search is invalid unless it is

supported by probable cause and is justified under one of the narrowly defined

exceptions to the warrant requirement.”). Our analysis thus begins with the presumption

that a warrantless search must be supported by probable cause and justified under an

exception to the warrant requirement.

¶51 “A police officer has probable cause to conduct a search when ‘the facts available

to [the officer] would warrant a [person] of reasonable caution in the belief’ that

contraband or evidence of a crime is present.” Zuniga, ¶ 16, 372 P.3d at 1057 (alterations

in original) (quoting Harris, 568 U.S. at 243). “[P]robable cause is a commonsense concept

that requires judges to consider the totality of the circumstances to determine ‘whether a

fair probability exists that a search of a particular place will reveal contraband or evidence

of a crime.’” Id. (quoting Mendez, 986 P.2d at 280). This standard does not “lend itself to

mathematical certainties,” and, instead, “is based on factual and practical considerations

of everyday life on which reasonable and prudent people, not legal technicians, act.”

29
Mendez, 986 P.2d at 280. But it is more demanding than reasonable suspicion. People v.

Polander, 41 P.3d 698, 703 (Colo. 2001) (“Reasonable suspicion is a less demanding

standard . . . not only in the sense that it can be established with information that is

different in quantity or content from that required for probable cause, but also in the sense

that reasonable suspicion can arise from information that is less reliable than that

required to show probable cause.”).

¶52 Reasonable suspicion still requires “specific and articulable facts, greater than a

mere hunch” to support a belief that a person was engaging in or had been engaged in

criminal activity. People v. Boylan, 854 P.2d 807, 812 (Colo. 1993), abrogated by Esparza, 2012

CO 22, 272 P.3d 367. An officer can conduct a brief, investigatory stop if he has reasonable

suspicion to believe that criminal activity “has occurred, is taking place, or is about to

take place.” People v. Ingram, 984 P.2d 597, 603 (Colo. 1999). And “[s]uspicion of even a

minor traffic offense can provide the basis for a stop.” People v. Chavez-Barragan, 2016 CO

16, ¶ 10, 365 P.3d 981, 983.

¶53 Two of the judges on the division below agreed that Kilo’s sniff was a search

requiring reasonable suspicion after looking back to the reasoning of our pre-Esparza

caselaw. McKnight, ¶¶ 19–20 (opinion by Dailey, J.) (citing sources). In Unruh, we

concluded that requiring reasonable suspicion to justify a dog-sniff search struck the

proper “balance” between the government’s interest in stopping the illegal narcotics

trade and an individual’s interest in being free from governmental search and seizure.

713 P.2d at 379. We reasoned that this was so because a dog’s sniff was less intrusive

than other forms of searches because it was “uniquely selective, detecting in most cases

30
only the presence of narcotics.” Id. If a dog alerted, in theory, it would only disclose to

the officers the presence of contraband—the sniff couldn’t disclose any specific details

regarding the lawful contents of a vehicle. Accordingly, we concluded the dog-sniff

search was minimally intrusive, and required only reasonable suspicion rather than

probable cause to utilize. Id.

¶54 However, Unruh, and the line of cases following, were decided when marijuana

was still wholly illegal under state law and, thus, a drug-detection dog’s sniff could only

uncover the presence or absence of illegal contraband. And perhaps at the time, treating

a sniff from a drug-detection dog as a minimally invasive search only necessitating

reasonable suspicion did balance the interests at stake.7 But that is no longer the case.

The sniff can now reveal details concerning lawful activity, the possession of up to an

ounce of marijuana by adults twenty-one and older. We see no reason to treat a search

that could reveal legal marijuana any differently from a search that could reveal other

lawful activity. Cf. Arizona v. Hicks, 480 U.S. 321, 328–29 (1987) (refusing to create a sort

of quasi-search that need only be justified by reasonable suspicion because it was less

intrusive than other search tactics). Regardless of the relative intrusiveness or

7We may have overstated the “minimally intrusive” nature of an exploratory sniff from
a drug-detection dog in our past cases. Justice Ginsburg put it bluntly in her dissent in
Caballes: “A drug-detection dog is an intimidating animal.” 543 U.S. at 421 (Ginsburg, J.,
dissenting). And she makes a good point. For the motorist stopped for a routine traffic
violation and then subjected to an exploratory sniff, the use of these four-legged law
enforcement tools “changes the character of the encounter between the police and the
motorist. . . . [it] becomes broader, more adversarial . . . .” Id.

31
invasiveness, if law enforcement action constitutes a search, it must be authorized by a

warrant from a neutral magistrate or justified by an exception to the warrant requirement

and supported by probable cause.

¶55 Thus, we conclude that a sniff from a dog trained to alert to marijuana is a search

in Colorado that must be supported by probable cause and justified under an exception

to the warrant requirement, such as the automobile exception.

F. There Was No Probable Cause for Kilo’s Search

¶56 So before Kilo’s alert, what factors suggested there was probable cause to believe

McKnight’s car contained illegal narcotics under state law? The People emphasize that

McKnight parked outside a house in which drugs had been found and that Officer

Gonzales knew that McKnight’s passenger had used methamphetamine in the past. But

McKnight’s decision to park near the house tells us little, considering that almost

two months had passed since drugs were found there. See People v. Miller, 75 P.3d 1108,

1114–15 (Colo. 2003) (concluding that information about alleged criminal activity that

was nearly a month old was too “stale” to provide probable cause for a search warrant).

Moreover, even if we were to speculate (without record support) that the house was and

remained a drug den, the record reveals that, on the evening in question, no one exited

the truck or the house. Therefore, the People’s observation that McKnight stopped his

vehicle long enough to effectuate a drug deal and use any substance that had been bought

is irrelevant. And we have consistently rejected the notion that “a history of past criminal

activity in an area is itself sufficient to create a reasonable suspicion that a crime is being,

has been, or will be committed.” Outlaw v. People, 17 P.3d 150, 157 (Colo. 2001) (citing

32
People v. Greer, 860 P.2d 528, 531 (Colo. 1993); People v. Rahming, 795 P.2d 1338, 1342 (Colo.

1990)). If “a history of past criminal activity in an area” wasn’t enough on its own to

establish reasonable suspicion of criminal activity, then it also wouldn’t be enough on its

own to satisfy the more stringent standard of probable cause.

¶57 As for the passenger’s drug history, Officer Gonzales could offer no details. All

he could say with certainty is that whatever drug usage he recalled “wasn’t super recent.”

The People encourage us to take notice of how difficult it is to overcome

methamphetamine addiction and to extrapolate that the passenger was still using. On a

record so lacking in details, we decline the invitation. Even if we accepted, it isn’t clear

that it would yield probable cause to believe that contraband would be found in the truck.

Cf. Greer, 860 P.2d at 531 n.2 (citing Sibron v. New York, 392 U.S. 40, 62–63 (1968) (“The

inference that persons who talk to narcotics addicts are engaged in the criminal traffic in

narcotics is simply not the sort of reasonable inference required to support an intrusion

by the police upon an individual’s personal security.”)); People v. Feltch, 483 P.2d 1335,

1337 (Colo. 1971) (rejecting “the theory that birds of a feather flock together” and stating

“[g]uilt by association has never been an acceptable rationale and it does not constitute

probable cause to arrest”). We are loathe to create a rule that would allow police to

randomly search known drug users. Cf. Robinson v. California, 370 U.S. 660, 666–68 (1962)

(holding that a California statute that criminalized narcotic addiction itself was

unconstitutional). In other words, drug users have the same constitutional rights as

everyone else.

33
¶58 The question becomes: Are (1) proximity to a house in which drugs had been

found nearly two months earlier, and (2) the presence of someone who “at some point”

had used an illegal drug enough to establish a fair probability that contraband under state

law would be found in McKnight’s truck on the evening in question, thus justifying Kilo’s

sniff? Even when considered together, these two facts are insufficient to establish

probable cause to believe McKnight’s truck contained illegal narcotics under state law.

We can look to Zuniga for an illuminating comparison. There we found probable cause

to search a car because the driver and passenger had “divergent” stories about their visit

to Colorado, they were “extreme[ly] nervous[],” there was a “strong odor of raw

marijuana,” and a drug-detection dog alerted at the back of the vehicle. Zuniga, ¶ 1, 372

P.3d at 1054. Though we did not need to resolve whether the sniff constituted a search

in that case, we noted that an alert alone was ambiguous in light of Amendment 64. Id.

at ¶¶ 20–21. And the totality of the circumstances—the “differing” stories, the

“exceptional” nervousness, and the strong scent of unburnt marijuana that the officer was

able to smell with his own nose—supported the officer’s conclusion that there was a fair

probability that a search would reveal evidence of a crime. Id. Here though, without

Kilo’s alert, the officers just observed McKnight’s truck near a house where the last

documented criminal activity occurred nearly two months before and McKnight’s

passenger was a person who had used illegal drugs at some point in the not “super

recent” past. That isn’t enough to warrant the sniff, or the subsequent intrusion into

McKnight’s truck. See Greer, 860 P.2d at 531 & n.2.

34
¶59 Thanks to the subsequent hand search of McKnight’s truck, which only revealed

the pipe with methamphetamine residue, we can infer that Kilo was not alerting to the

scent of lawfully possessed marijuana. But, as noted at the outset of our analysis, we

don’t measure a search’s constitutionality by looking at what it reveals. Rather, we

examine the constitutionality of a search based on what was known at the time it was

conducted.

¶60 And, like the division, we cannot conclude that “the evidence properly received

against [McKnight was] so overwhelming that the constitutional violation was harmless

beyond a reasonable doubt.” McKnight, ¶ 24 (opinion of Dailey, J.) (citing Bartley v. People,

817 P.2d 1029, 1034 (Colo. 1991)). Indeed, the People do not contend otherwise. Opening

Brief at 10 (“The People concede that if this Court [were] to find that the trial court erred

in denying McKnight’s suppression motion, the error could not be harmless.”).

G. Exclusion of the Pipe Is the Remedy for this Violation of the
Colorado Constitution

¶61 Exclusion is the appropriate remedy for this constitutional violation. Though we

have previously affirmed suppression orders excluding evidence obtained in violation of

article II, section 7, we have not explicitly addressed whether we adopted a state corollary

to the federal exclusionary rule. See, e.g., Oates, 698 P.2d at 816, 819 (Colo. 1985) (affirming

the suppression of evidence obtained from an illegal search under article II, section 7,

without expressly analyzing exclusion as the remedy). Yet, in affirming suppression of

evidence obtained in violation of article II, section 7, we have implied that we are open to

finding exclusion to be the proper remedy for violations of state constitutional law. See

35
Corr, 682 P.2d at 22, 27–28 (rejecting the application of the statutory good faith exception,

and in affirming the suppression of toll telephone call records obtained in violation of

article II, section 7, suggesting we approved of exclusion as the remedy); see also 1 Wayne

R. LaFave, Search & Seizure: A Treatise on the Fourth Amendment § 1.5(b) (5th ed. Oct. 2018

update) (noting that state courts often suppress evidence obtained in violation of state

constitutional prohibitions against unreasonable searches and seizures while “seldom”

explaining their rationale for concluding “that the exclusionary remedy is just as

appropriate [for state law violations] as when the Fourth Amendment is violated”). To

the extent that we have not yet explicitly embraced the exclusionary rule as a remedy for

violations of article II, section 7, we do so now. We recognize that the federal courts have

created several exceptions to the exclusionary rule, see, e.g., United States v. Leon, 468 U.S.

897 (1984), and that we have our own statutory good-faith exception, see § 16-3-308, C.R.S.

(2018), but we need not address the applicability of those exceptions. Because the

prosecution did not raise any arguments about the exclusionary rule or its exceptions at

the suppression hearing, we consider those arguments waived and decline to address

them on appeal. See People v. Crippen, 223 P.3d 114, 116–17 (Colo. 2010); People v. Donahue,

750 P.2d 291, 293 (Colo. 1988).

III. Conclusion

¶62 We hold that a sniff from a drug-detection dog that is trained to alert to marijuana

constitutes a search under article II, section 7 of the Colorado Constitution because that

sniff can detect lawful activity, namely the legal possession of up to one ounce of

marijuana by adults at least twenty-one years old. We further hold that, in Colorado, law

36
enforcement officers must have probable cause to believe that an item or area contains a

drug in violation of state law before deploying a drug-detection dog that alerts to

marijuana for an exploratory sniff. Because there was no such probable cause justifying

Kilo’s search of McKnight’s truck, the trial court erred in denying McKnight’s motion to

suppress.

¶63 This holding is based solely on the protections afforded by our state constitution,

and to the extent we discuss any federal cases in coming to our conclusion, it is only for

the purpose of analogy and comparison. See Michigan v. Long, 463 U.S. 1032, 1040–41

(1983).

¶64 Accordingly, we affirm the court of appeals’ decision to reverse McKnight’s

judgment of conviction.

CHIEF JUSTICE COATS dissents, and JUSTICE BOATRIGHT and JUSTICE
SAMOUR join in the dissent.
JUSTICE SAMOUR dissents, and JUSTICE BOATRIGHT joins in the dissent.

37
CHIEF JUSTICE COATS, dissenting.

¶65 Apart from my objections to much of the majority’s selective and at times

revisionist promenade through the history of both federal and state search and seizure

law, I object specifically to its radical reconstruction, in the wake of our recent marijuana

initiative, of the state’s own constitutional Bill of Rights. Although the majority does its

best to avoid addressing the issue, I believe the most significant aspect of its rationale

today concerns the question of federal supremacy, the nature and scope of which may be

more at issue today, in various contexts, than has been the case at any time in the last

hundred and fifty years. Because I not only disagree with the majority’s outcome here

but also consider its reasoning both deeply flawed and likely to have implications far

beyond this case, I respectfully dissent and briefly outline the more significant of my

objections.

¶66 I must begin, however, by registering my emphatic objection to the majority’s

gratuitous and wholly unjustified assertion that our prior decisions had already

effectively foreclosed the possibility that the alert of a trained drug detection dog alone

can any longer provide probable cause of the presence of contraband and therefore

probable cause of the commission of a crime. In both People v. Zuniga, 2016 CO 52, ¶ 30

n.6, 372 P.3d 1052, 1060 n.6, and People v. Cox, 2017 CO 8, ¶ 22 n.5, 401 P.3d 509, 514 n.5,

we expressly reserved the question, finding its resolution unnecessary in those cases,

where there were other grounds establishing probable cause to search in addition to or

in conjunction with the dog alert. The majority’s suggestion that an appellate court’s

choice among alternate rationales to resolve an assignment of error implicitly indicates

1
that all other possible rationales would be inadequate bespeaks a fundamental

misconception about appellate practice and precedent, if not simply language and logic.

In any event, the majority rationale today is a far cry from simply finding that a dog’s

inability to distinguish among quantities of marijuana deprives its alert of the capability,

in and of itself, of establishing probable cause to believe that more than an ounce of the

drug is present.

¶67 Lest the wheat of the real issue of the case be lost amongst the chaff, I emphasize

the question upon which the majority actually resolves this case, which I understand to

be whether the state constitution has now not only legalized the possession of small

amounts of marijuana by adults in the state but has in fact shrouded such possession with

an expectation of privacy such that its detection by police investigation within the

territorial boundaries of this state amounts to the detection of “lawful” activity, despite

the proscription of the very same activity as “unlawful” according to the coordinate

federal criminal law. It seems clear that even the majority does not dispute the

well-established proposition that the use of investigative techniques or devices, in this

case a dog, capable of observing nothing more than activity that is unlawful, does not

constitute a search within the contemplation of either the Fourth Amendment of the

federal constitution or article II, section 7 of the state constitution. See Illinois v. Caballes,

543 U.S. 405, 408–09 (2005); People v. Esparza, 2012 CO 22, ¶ 11, 272 P.3d 367, 370. The

specific wrinkle posed by our recent, popularly-initiated amendment to the state

constitution is whether a dog sniff, despite being capable of exposing no more than the

presence of federal contraband, nevertheless constitutes a search within the contemplation

2
of the state constitution for the reason that it can detect the presence of a small amount of

marijuana possessed by an adult, which is now lawful under state law.

¶68 In Coats v. Dish Network, LLC, 2015 CO 44, ¶ 20, 350 P.3d 849, 853, we addressed

the similar question whether the General Assembly intended to extend the protections

for “lawful” activities afforded by section 24-34-402.5, C.R.S. (2018), to activities made

lawful under state law but remaining unlawful under federal law. We there concluded

that the term “lawful” could not have been intended to include the possession of

marijuana that remains “unlawful” under federal law, Coats, ¶ 20, 350 P.3d at 853, which

in our federal system not only applies in this jurisdiction but, in the event of conflict,

actually reigns supreme over state law. Today, the majority holds instead that a dog sniff

capable of exposing the lawful presence of marijuana under state law, but no more than

the possession of contraband—unlawful activity—under federal law, nevertheless

constitutes a search within the contemplation of the state constitution, requiring probable

cause and either a warrant or an exception thereto.

¶69 In the last half-century, the Supreme Court has come to construe the language of

the Fourth Amendment protecting the “right of people to be secure in their persons,

houses, papers, and effects against unreasonable searches and seizures,” as intending to

broadly protect any reasonable expectation of privacy whatsoever, see Katz v. United

States, 389 U.S. 347, 361 (1967) (Harlan, J., concurring), which concept it has subsequently

defined to include any subjective expectation of privacy that society is prepared to

recognize as reasonable, California v. Ciraolo, 476 U.S. 207, 211 (1986). Although without

elaboration, on several occasions in the past, we apparently not only subscribed to this

3
broad construction of the words “persons, houses, papers, and effects,” by understanding

article II, section 7 as similarly protecting any reasonable expectation of privacy but, in

addition, accepted as reasonable certain expectations considered unreasonable by the

Supreme Court. See Charnes v. DiGiacomo, 612 P.2d 1117, 1121 (Colo. 1980) (finding

reasonable expectation of privacy and therefore protection under the state constitution

for records in the hands of banks); see also People v. Oates, 698 P.2d 811, 818–19 (Colo. 1985)

(same for purchase of drug precursors); People v. Corr, 682 P.2d 20, 27 (Colo. 1984) (same

for phone records); People v. Sporleder, 666 P.2d 135, 144 (Colo. 1983) (same for numbers

of incoming phone calls detected by pen register). Today, following its paean to separate

reliance on state constitutions, the majority construes our constitution, in conjunction

with the regulatory framework created for its implementation, as not only

decriminalizing the possession of small amounts of marijuana but also as reflecting a state

policy adopting the proposition that an adult’s subjective expectation of privacy in his

possession of an amount of marijuana legal under state law must be considered

objectively reasonable, with the effect that in Colorado such an individual is held to have

a reasonable expectation of privacy in the commission of federal crime. Not only do I not

share this view of state law as designating such a subjective expectation of privacy

reasonable, but perhaps even more importantly, I do not share the majority’s view that

the marijuana amendments and regulations upon which it relies were intended to alter

our prior interpretation of article II, section 7 with regard to the use of investigative

techniques capable of detecting no more than unlawful activity.

4
¶70 Initially, I consider thoroughly unpersuasive the majority’s patchwork of

conclusory propositions in support of its conclusion that Amendment 64 not only

legalized certain activities related to marijuana but in fact “expanded the protections of

article II, section 7 to provide a reasonable expectation of privacy to engage in the lawful

activity of possessing marijuana in Colorado.” Maj. op. ¶ 42. The amendment, of course,

does not cross-reference the constitutional search and seizure provision at all; does not in

any way allude to an expectation of privacy in the possession of marijuana, much less a

reasonable expectation of privacy in violating federal law; and does not remotely suggest

the imposition of any restriction on state executive branch officers from detecting federal

crime. Furthermore, the sole reference to “individual privacy” mentioned by the majority

is limited to an express prohibition against the promulgation of regulations mandating

the collection of personal data by retailers as a precondition to sale. Maj. op. ¶ 41.

¶71 Even if it were plausible to construe our regulatory scheme as intending to create

a special expectation of privacy in the possession of marijuana, as does the majority,

however, I can perceive nothing (and the majority offers nothing) in that construction

requiring us to alter the calculus governing our decision in Coats. Just as in Coats, ¶ 20,

350 P.3d at 853, the question upon which the majority’s ultimate holding turns is whether

the possession of marijuana can be considered “lawful” activity in this context, despite

its continued proscription as criminal by federal law—law which also governs this

jurisdiction. In this regard, I consider the majority’s reliance on a separate state

constitutional expectation of privacy in the possession of marijuana to be superfluous, in

no way rendering the possession of federal contraband in the state “lawful.”

5
¶72 In particular, the majority notes a line of cases decided more than thirty years ago

in which we held as a matter of state constitutional law that an individual does not

abandon a reasonable expectation of privacy simply by exposing otherwise private

information to third parties no more than is necessary to participate and conduct business

in the modern world. See Oates, 698 P.2d at 818–19 (exposing the purchase of drug

precursors to the chemical wholesaler); Corr, 682 P.2d at 26–27 (exposing numbers of

outgoing calls to phone company); Sporleder, 666 P.2d at 144 (exposing numbers of

incoming calls to phone company); DiGiacomo, 612 P.2d at 1121 (exposing banking

transactions to the bank). While there can be no question that states may, and when

appropriate should, afford even greater protections to their citizenry than those already

afforded by the federal Bill of Rights, see Curious Theatre Co. v. Colo. Dep’t of Pub. Health &

Env’t, 220 P.3d 544, 551 (Colo. 2009), by the same token states are clearly not empowered

to enact laws that conflict with federal law, see Wyeth v. Levine, 555 U.S. 555, 563 (2009).

Nor have we ever suggested anything of the sort. Unless the majority intends to equate

affording protections beyond those rights already afforded under the federal Bill of

Rights with affording protections for violating federal law, I fail to see how its discussion

of our past reliance on state constitutional grounds in any way advances its analysis.

Unlike the majority, I do not believe the language of the marijuana initiative, even when

considered in conjunction with other constitutional or statutory provisions, can be

understood to recognize a reasonable expectation of privacy in committing federal crime,

and I consider it clear that this court has never, for obvious reasons, interpreted article II,

section 7 to sanction any such expectation.

6
¶73 Beyond extending in this way, without acknowledgement or justification of any

kind, the effect of reliance on state constitutional grounds, the majority also overturns

long-accepted precedent of the jurisdiction, similarly without acknowledgement or

justification of any kind, by announcing, ex cathedra, that we now will “embrace[] the

exclusionary rule as a remedy for violations of article II, section 7.” Maj. op. ¶ 61.

Although, as the majority indicates, we have on several occasions in the past affirmed

suppression orders of lower courts as the result of violations of expectations of privacy

recognized as reasonable solely under the state constitution, see Oates, 698 P.2d at 812;

Corr, 682 P.2d at 22; Sporleder, 666 P.2d at 136, we have never suggested the existence of a

separate exclusionary rule for violation of the state constitution. Whether the absence of

any justification for adopting the suppression orders in those cases reflects an assumption

that the exclusionary remedy adopted by the Supreme Court would require the

suppression of an unjustified infringement on any reasonable expectation of privacy,

regardless of its source, or reflects simply the absence of any express challenge to the

affirmance of the lower courts’ exclusionary orders, it is clearly substantially more

problematic, even to the majority, to order the exclusion of evidence for violation of a

state-recognized expectation of privacy in committing federal crime, without expressly

resting that remedy in state law.

¶74 The last time this court expressly considered the question whether our

constitutional guarantee against unreasonable searches implied its own exclusionary

remedy, we firmly rejected that proposition. See Wolf v. People, 187 P.2d 926, 927–28

(1947), aff’d, Wolf v. Colorado, 338 U.S. 25 (1949), overruled by Mapp v. Ohio, 367 U.S. 643

7
(1961) (concerning the applicability in state criminal proceedings of the exclusionary rule

adopted in Weeks v. United States, 232 U.S. 383 (1914), for evidence seized in violation of

the Fourth Amendment). While we expressly rejected any exclusionary rule of evidence

for violation of article II, section 7 in Wolf, this was not the only or first time we did so,

see Roberts v. People, 243 P. 544, 559 (Colo. 1926); Massantonio v. People, 236 P. 1019, 1021

(Colo. 1925), and we continued to reject the exclusion of evidence for violation of

constitutional search provisions until ordered to apply the Fourth Amendment

exclusionary rule in Mapp, see Williams v. People, 315 P.2d 189, 191 (Colo. 1957).

¶75 This court first rejected exclusion as a remedy for a violation of article II, section 7

in Massantonio, 236 P. at 1021, largely reasoning that the rule in Weeks was fundamentally

flawed because the Fourth Amendment violation occurs when the illegal seizure

happens, not when the evidence is used at trial; because there is nothing about the

constitutional violation itself that renders the evidence incompetent; and because the rule

contradicted the fundamental principle accepted at law that an illegality in the mode of

procuring evidence is no ground for excluding it. We reaffirmed Massantonio in Roberts,

243 P. at 559, noting that the exclusionary rule had been rejected “after a thorough

examination of all the available authorities and a careful consideration of the alleged

reasons supporting each.” Roberts also noted that, in addition to the logical errors made

by the rule, it also lacked policy justification because it could, for instance, allow “one

unquestionably guilty of an atrocious murder” to be “turned loose.” Id.

¶76 In the absence of offering any rationale or justification for reversing course and

now adopting an exclusionary remedy for violation of article II, section 7, the majority

8
necessarily offers no hint about the nature and applicability of its new rule, beyond the

fact that it will require the suppression of the meth pipe discovered in this case. Even the

federal exclusionary rule itself is no longer a bright-line rule of automatic exclusion,

having now been declared “a judicially created remedy designed to safeguard Fourth

Amendment rights generally through its deterrent effect, rather than a personal

constitutional right of the party aggrieved.” United States v. Calandra, 414 U.S. 338, 348

(1974). In the ensuing years, the Supreme Court has expressly recognized a host of

limitations and exceptions to exclusion, including the inapplicability of the rule in whole

classes of proceedings, see Stone v. Powell, 428 U.S. 465, 494 (1976) (habeas corpus

proceedings); United States v. Janis, 428 U.S. 433, 459–60 (1976) (civil proceedings);

Calandra, 414 U.S at 354 (grand jury proceedings); its inapplicability to the fruits of an

unlawful search under various circumstances, see Nix v. Williams, 467 U.S. 431, 444 (1984)

(inevitable discovery); Silverthorne Lumber Co. v. United States, 251 U.S. 385, 392 (1920)

(independent source); and even its ineffectiveness where otherwise applicable, see

Herring v. United States, 555 U.S. 135, 137, 147 (2009) (negligence as to accuracy of active

warrants); Hudson v. Michigan, 547 U.S. 586, 594 (2006) (violations of knock-and-announce

rule); Arizona v. Evans, 514 U.S. 1, 12–14 (1995) (clerical errors); United States v. Leon, 468

U.S. 897, 918–21 (1984) (good faith execution of defective warrants). In addition, the

Supreme Court has made clear that even where no specific exception has been

recognized, the rule may not apply if its potential deterrent benefits do not merit its costs.

Herring, 555 U.S. at 140 (citing Hudson, 547 U.S. at 591). Whether the new Colorado rule

will follow the continuing evolution of the federal rule, or whether it will simply become

9
another vehicle for disagreeing with the Supreme Court or providing insulation from its

review, for now must apparently remain a mystery.

¶77 The legal justification for, or even policy benefits of, adopting an exclusionary rule

as a means of modifying executive branch behavior having no impact on the competence

of the evidence itself is hardly self-evident or a matter to be casually decided without

vigorous debate. Both sides of the political spectrum have argued against the use of the

federal exclusionary rule, despite its having been in existence for more than a century.

See Christopher Slobogin, Why Liberals Should Chuck the Exclusionary Rule, 1999 U. Ill. L.

Rev. 363, 365–66 (1999) (arguing that exclusion is appropriate only for flagrant violations

and that monetary liability for individual officers and police departments would better

deter Fourth Amendment violations); Patrick Tinsley, N. Stephan Kinsella & Walter

Block, In Defense of Evidence and Against the Exclusionary Rule: A Libertarian Approach, 32

S.U. L. Rev. 63, 72 (2004) (arguing that removing exclusionary rule and instead allowing

for damages suits would be more effective and would allow non-criminal victims of

Fourth Amendment violations to have a remedy); see also Janis, 428 U.S. at 448–53

(discussing difficulties in evaluating deterrence).

¶78 In addition, a number of substantial arguments have arisen specifically against the

adoption of separate state constitutional exclusionary rules. See, e.g., Paul G. Cassell, The

Mysterious Creation of Search and Seizure Exclusionary Rules Under State Constitutions: The

Utah Example, 1993 Utah L. Rev. 751, 756–58 (1993); Robert M. Pitler, Independent State

Search and Seizure Constitutionalism: The New York State Court of Appeals’ Quest for Principled

Decisionmaking, 62 Brook. L. Rev. 1, 174–80 (1996). Pitler articulates a number of

10
objections to a judicially created exclusionary rule by New York’s highest court, including

1) various arguments raised against such a rule at one of New York’s constitutional

conventions, 2) precedent refusing to recognize an exclusionary rule, 3) common law

evidentiary principles that reliable evidence should be admitted to further the

truth-finding process, and 4) the inherently policy-based nature of the rule. Pitler, supra,

at 174–75. Focusing on Utah’s judicially created exclusionary rule, Cassell also provides

a useful framework from which courts might analyze the question whether exclusion is

an appropriate remedy under a state constitution, arguing essentially that state courts are

obliged to begin by considering the intent of the framers of their own constitution’s search

and seizure provision, through traditional constitutional precepts of interpretation.

Cassell, supra, at 757. Equally applicable to the question in this jurisdiction is his

admonition that state courts must also consider whether an exclusionary rule is consistent

with the state’s separation of powers doctrine and rules of evidence, as well as whether

such a rule would be sound from a state public policy perspective. Id. Finally, the

availability and effectiveness of other remedies for search and seizure violations cannot

be discounted in any meaningful assessment. Id. at 758.

¶79 Similarly, state high courts, including this court in particular, have been cautioned

in adopting an exclusionary rule to avoid tying themselves too tightly to the federal rule

as applied by the Supreme Court, given the haphazard and inconsistent evolution of that

rule. See Michael K. Schneider, An Exclusionary Rule Colorado Can Call Its Own, 63 U. Colo.

L. Rev. 207, 208 (1992); see also Jeffrey S. Sutton, 51 Imperfect Solutions: States and the

Making of American Constitutional Law 42–83 (2018) (recounting the development of the

11
federal exclusionary rule and encouraging state courts not to assume federal courts can

best protect the constitutional rights of criminal defendants). Having done so itself, at

least one state high court cautions that whatever process a state court uses to adopt or

reject a state exclusionary rule, at the very least it should consider basic questions: 1) What

is the basis of the rule—is it a constitutional right, merely a judicial remedy, or

constitutionally compelled?; 2) What are the purposes behind the rule—deterrence alone

or something else?; and 3) Who is meant to be deterred—police only or other persons in

the criminal justice system? See State v. Larocco, 794 P.2d 460, 473 (Utah 1990) (plurality

opinion) (adopting state exclusionary rule); see also Sanford E. Pitler, The Origin and

Development of Washington’s Independent Exclusionary Rule: Constitutional Right and

Constitutionally Compelled Remedy, 61 Wash. L. Rev. 459, 460 (1986) (finding that state

courts typically justify an exclusionary rule of evidence as a separate constitutional right,

as a judicially created remedy, or as compelled by the applicable constitutional

provision).

¶80 Beyond what I consider to be its logical flaws, legal misinterpretations, and

intemperate extensions of state constitutional doctrine, however, I am particularly

concerned that in going to such lengths to craft a rationale for imposing limitations on

the use of drug detection dogs, the majority unwittingly exposes not only the marijuana

initiative itself but even the state’s constitutional Bill of Rights to a much greater risk of

federal preemption than would previously have been the case. Whether or not the

legalization and regulation of marijuana and the majority’s construction of the state’s Bill

of Rights in the wake of those actions are of a piece, such that the majority’s resolution

12
today could in any way have been anticipated, I do not consider it appropriate, or wise,

to sidestep what I believe to be the most significant impediment to the majority’s

rationale. While resting a decision solely on state grounds may generally be an effective

technique for insulating state courts from further federal review, that is clearly not the

case with regard to the supremacy of federal law.

¶81 Any federal system of government must of course have some strategy for dealing

with conflicts between the national and local governments, and the framers of our federal

constitution embodied their choice of strategy in the Supremacy Clause, U.S. Const. art.

VI, cl. 2. Although the rules developed by the Supreme Court for determining the

existence of an irreconcilable conflict requiring resolution in favor of federal law may be

complex and at times unclear, even before today’s construction we had found at least a

portion of Amendment 64 to be preempted by federal law. See People v. Crouse, 2017 CO

5, ¶ 19, 388 P.3d 39, 43. Whether the recent marijuana law, on its face or as construed to

impact article II, section 7, “stands as an obstacle to the accomplishment and execution

of the full purposes and objectives of Congress,” Hines v. Davidowitz, 312 U.S. 52, 67

(1941); see also People v. Crouse, 2013 COA 174, ¶ 91, 412 P.3d 599, 616 (Bernard, J.,

concurring in part and dissenting in part), rev’d, 2017 CO 5, 388 P.3d 39, appears to be a

question that will have to wait for another day, but I believe that after today, that question

cries out for resolution more than ever before.

¶82 Because I believe that a straightforward application of Zuniga and Esparza require

that the trial court’s denial of the motion to suppress be affirmed, I would reverse the

judgment of the court of appeals.

13
¶83 I therefore respectfully dissent.

I am authorized to state that JUSTICE BOATRIGHT and JUSTICE SAMOUR join

in this dissent.

14
JUSTICE SAMOUR, dissenting.

¶84 Today the majority concludes that a dog sniff of the public air outside a car, though

not a search under the Federal Constitution, is a search under the Colorado Constitution

because Amendment 64 legalized the possession of marijuana in limited circumstances.

However, in doing so, the majority skirts a critical question in the analysis: Does a driver

have a reasonable expectation of privacy in the odors that escape from his car and become

part of the public airspace? Instead, the majority: (1) draws an unwarranted inference

from Illinois v. Caballes, 543 U.S. 405 (2005); and (2) analogizes a dog sniff of the public air

outside a lawfully stopped car to the use of a thermal-imaging device aimed at a private

home to detect relative amounts of heat inside. And, to boot, the majority purports to

nestle its ruling in the Colorado Constitution when it is clearly anchored to Fourth

Amendment jurisprudence. Accordingly, while I wholeheartedly join the Chief Justice’s

well-reasoned dissent, I write separately to express additional bases of disagreement with

the majority’s decision.

I. Overview

¶85 The majority’s flawed reasoning goes something like this:

(1) the Fourth Amendment protects people from unreasonable searches and
seizures, and warrantless searches are presumed unreasonable and,
therefore, unconstitutional;

(2) the U.S. Supreme Court held in Katz v. United States, 389 U.S. 347 (1967),
that a search under the Fourth Amendment occurs when the government
violates a subjective expectation of privacy that society recognizes as
reasonable;

1
(3) Amendment 64 created a reasonable expectation of privacy in the
possession of an ounce or less of marijuana by adults twenty-one and older
in Colorado;

(4) McKnight was older than twenty-one when his car was lawfully
stopped;

(5) therefore, officers violated McKnight’s rights under the Colorado
Constitution (article II, section 7) when they had Kilo—a dog trained to
detect the odor of drugs (including marijuana)—sniff the public air around
his car without a warrant.

¶86 Even assuming Amendment 64 created the reasonable expectation of privacy the

majority says it did, the majority’s analysis is incomplete. To be sure, under the U.S.

Supreme Court case law on which the majority opinion rests, McKnight had a reasonable

expectation of privacy in any noncontraband items in his car. (Although I agree with the

Chief Justice’s views, I assume for purposes of this dissent that possession of up to an

ounce of marijuana by someone who is at least twenty-one qualifies as noncontraband in

Colorado after the passage of Amendment 64). Even so, that leaves a question still to be

answered: Did McKnight also have a reasonable expectation of privacy (under the

Colorado Constitution or any other authority) in odors that emanated from noncontraband

items in his car and escaped into the infinite public air outside? The majority circumvents this

question, overlooking a focal point of the relevant inquiry: the nature of the place

subjected to the dog sniff. After all, whether a dog sniff violates someone’s reasonable

expectation of privacy depends in large part on the place sniffed—be it a safe in a home,

luggage at an airport, a trash can in a public park, a laundry bag in a correctional facility,

or the air outside a car during a lawful traffic stop. If focusing solely on the privacy

2
interest in the item that an officer’s investigative technique (here, a dog sniff) is aimed at

detecting or locating (here, drugs, including marijuana) was sufficient, it would lead to

absurd results.

¶87 The majority relies heavily on the U.S. Supreme Court’s decision in Caballes (and

on our adoption of its rationale in People v. Esparza, 2012 CO 22, 272 P.3d 367). But, while

Caballes dealt with a dog sniff of the exterior of a car during a lawful traffic stop, it did

not have to resolve the question that is front and center in this case because marijuana

was illegal in Illinois when Caballes was decided. It sufficed to hold in Caballes that no

search had occurred because the dog sniff could have detected only the presence or

absence of contraband, and no person can ever have a legitimate expectation of privacy

in contraband. That approach cannot dispose of this appeal. The majority nevertheless

assumes that, since the Court held in Caballes that the dog sniff was not a search because

it could only detect contraband, the Court must have also meant that a dog sniff like the

one here, which could detect a drug the majority now views as noncontraband, is a search.

¶88 In place of meaningful analysis regarding whether McKnight had a reasonable

expectation of privacy in the public air sniffed by Kilo, the majority analogizes Kilo’s sniff

to the use of a thermal imager that measures from the street the amount of heat inside a

private home, see Kyllo v. United States, 533 U.S. 27 (2001). The failure to accord these

drastically distinct factual scenarios the different treatment they deserve under the

Fourth Amendment and article II, section 7 leads the majority astray, eventually declaring

that the dog sniff here is as much a search under Katz as the thermal imaging of the home

3
in Kyllo. Kyllo is inapposite for two reasons: (1) a thermal-imaging scanner that detects

infrared radiation and converts it into images based on relative warmth can never be

confused with a dog’s nose; and (2) there is a night-and-day difference between a home

and a car.

¶89 To top it all off, the majority seeks cover under the cloak of the Colorado

Constitution. But the maneuver fails. While the legalization of marijuana pursuant to

Amendment 64 is clearly Colorado-specific, the majority’s search-and-seizure analysis is

not; rather, it is clearly predicated on U.S. Supreme Court precedent interpreting the

Fourth Amendment. The majority does not shepherd a new Colorado-only methodology

for determining what constitutes a search. To the contrary, it recognizes that the

applicable test is the one ushered in by the Court in Katz, it fastens its rationale to its

reading of Caballes, and it analogizes this case to Kyllo. Thus, what is unique to Colorado

in this case is the creation of an alleged new privacy interest in the possession of

marijuana in limited circumstances—a point I do not contest for purposes of this

dissent—not the adoption of a new analytical framework in the search-and-seizure arena

or the marshaling of a new constitutional scheme to protect against unreasonable

searches and seizures.

¶90 Using the Colorado Constitution as a broom, however, the majority attempts to

sweep under the rug the overwhelming authority from other jurisdictions directly

contravening its decision. Almost without exception, state and federal courts have held

that a driver has no reasonable expectation of privacy in odors that escape from his car

4
and are detected during a dog sniff of the public air outside. And no court has gone

against that grain for at least thirty years. In concluding that Kilo’s sniff was a search, the

majority bucks the trend and places this court on an island. In response, the majority says

that this island is one “on which Colorado voters have deposited us,” and that “[o]ur role

is not to question their decision.” Maj. op. ¶ 47. But the finger should not be pointed at

Colorado’s voters. They were not asked about search-and-seizure issues, much less about

dog sniffs, when they voted for Amendment 64.

¶91 Respectfully, I cannot join my colleagues in the majority. Instead, I would

conclude that, while a driver in Colorado has a reasonable expectation of privacy in any

noncontraband items and “lawful activity” in his car, id. at ¶ 3, he does not have a

reasonable expectation of privacy in odors that emanate from those items or activities

and escape into the infinite public air outside. Because McKnight had no reasonable

expectation of privacy in the public air sniffed by Kilo, Kilo’s sniff cannot be deemed a

search under the Fourth Amendment or article II, section 7. Thus, even if, as the majority

concludes, Amendment 64 created a reasonable expectation of privacy in the possession

of up to an ounce of marijuana by anyone who is at least twenty-one in Colorado, I would

hold that Kilo’s sniff of the odors in the free air outside McKnight’s car did not violate

the Federal or State Constitutions.

II. Analysis

¶92 At the outset, I note that there is no dispute that McKnight’s car was lawfully

stopped. The parties also agree that Kilo’s sniff did not unreasonably prolong the stop,

5
that Kilo never set paw in McKnight’s car, and that Kilo and his handler remained at all

times in a public place where they had a lawful right to be. Additionally, it is uncontested

that marijuana continues to be contraband under federal law. Given these circumstances,

my colleagues in the majority do not appear to contest that Kilo’s sniff is not a search

under the Fourth Amendment. Id. at ¶ 37.

¶93 The majority nevertheless throws out McKnight’s convictions for possession of

methamphetamine and paraphernalia because one of the five drugs Kilo was trained to

alert to was marijuana, and Amendment 64 legalized the possession of up to an ounce of

marijuana by adults who are at least twenty-one. To be clear, McKnight had no marijuana

in his car. But because he could have had marijuana in his car, and because it could have

been in an amount and under the limited circumstances permitted by state law, the

majority concludes that Kilo’s sniff intruded upon a reasonable expectation of privacy.

Though I fully embrace the Chief Justice’s dissent, I do not take issue with this

determination for purposes of my dissent. I focus, instead, on what I view as the most

glaring flaw in the majority opinion—the lack of meaningful analysis about whether

McKnight had a reasonable expectation of privacy in the odors that emanated from

noncontraband items or lawful activity in his car and exited into the boundless airspace.

After concluding that McKnight did not have a reasonable expectation of privacy in the

infinite public air outside his car, I discuss the strained inference the majority draws from

Caballes. I then refute the majority’s inapt comparison of this case to Kyllo. And I end by

demonstrating that, no matter the majority’s insistence to the contrary, its decision is

6
rooted in Fourth Amendment jurisprudence, prominently featuring three U.S. Supreme

Court cases— Katz, Caballes, and Kyllo—and nothing in the Colorado Constitution can

insulate it from attack.

A. There is No Reasonable Expectation of Privacy in an
Odor That Escapes from a Car

¶94 Does a driver have a reasonable expectation of privacy (under the Colorado

Constitution or any other authority) in an odor emitted by a noncontraband item or

lawful activity in his car after it has escaped into the public airspace outside? The

majority sidesteps the question and holds instead that a sniff from a drug-detection dog

trained to alert to marijuana is a search under article II, section 7 because, following the

passage of Amendment 64, “that sniff can detect lawful activity, namely the legal

possession of up to one ounce of marijuana by adults twenty-one and older.” Id. at ¶ 7.

Thus, my colleagues in the majority focus exclusively on the reasonable expectation of

privacy in the possession of an ounce or less of marijuana by anyone in Colorado who is

at least twenty-one.

¶95 But that cannot be the end of the discussion. Doesn’t the place sniffed matter?

Doesn’t it matter whether a dog sniff occurs inside a home, in an airport, in a public park,

in a correctional institution, outside a car, or somewhere else? And, as relevant here,

doesn’t it matter that Kilo never entered McKnight’s car but merely sniffed the public air

outside? Without meaningfully considering the place sniffed and whether McKnight had

a reasonable expectation of privacy there, we cannot properly discern if Kilo’s sniff

violated the Fourth Amendment or article II, section 7. Yet, without conducting the
7
required analysis, today’s decision prohibits all sniffs in Colorado by dogs with Kilo’s

training, unless there is probable cause to conduct a search.1 I undertake here the analysis

the majority ignores.

¶96 The jumping-off point is the test articulated by the U.S. Supreme Court in Katz

more than fifty years ago to determine whether a search occurred for purposes of the

Fourth Amendment—namely, whether the government’s activities violated a reasonable

expectation of privacy and thus constituted a search within the meaning of the Fourth

Amendment. Katz, 389 U.S. at 361 (Harlan, J., concurring).2 On this, there is no

disagreement. See maj. op. ¶ 22. Under Katz, no search occurs for Fourth Amendment

purposes unless “the individual manifested a subjective expectation of privacy” that

“society [is] willing to recognize . . . as reasonable.” California v. Ciraolo, 476 U.S. 207, 211

(1986); see also Katz, 389 U.S. at 361 (Harlan, J., concurring). In Katz, government agents

1 By requiring probable cause, a standard neither party advocated for in this case, the
majority sua sponte renders sniffs by dogs trained to detect marijuana largely obsolete. In
most cases, there will be no need for a dog sniff if officers already possess probable cause
to conduct a hand search.
2 The reasonable-expectation-of-privacy analysis in Katz makes clear that “property rights
‘are not the sole measure of Fourth Amendment violations.’” Florida v. Jardines, 569 U.S.
1, 5 (2013) (quoting Soldal v. Cook Cty., 506 U.S. 56, 64 (1992)). But, while “Katz may add
to the baseline, it does not subtract anything from the Amendment’s protections ‘when
the Government does engage in [a] physical intrusion of a constitutionally protected
area.’” Id. (quoting United States v. Knotts, 460 U.S. 276, 286 (1983) (Brennan, J., concurring
in the judgment only) (alteration in original). Here, there is no allegation that McKnight’s
property rights were violated or that the police physically invaded a constitutionally
protected area.
8
placed an electronic listening and recording device on the outside of a public telephone

booth in order to eavesdrop on Katz’s conversations. Katz, 389 U.S. at 348 (majority

opinion). The Court held that this was a search because Katz had “justifiably relied” on

the privacy of the telephone booth and thus had a reasonable expectation of privacy. Id.

at 353.

¶97 Of course, “[w]hat a person knowingly exposes to the public, even in his own

home . . ., is not a subject of Fourth Amendment protection.” Id. at 351; see also id. at 361

(Harlan, J., concurring) (“[O]bjects, activities, or statements that [a person] exposes to the

‘plain view’ of outsiders are not ‘protected’ because no intention to keep them to himself

has been exhibited”; conversations in the open, which may be overheard, are not

protected either because “the expectation of privacy under the circumstances would be

unreasonable.”). But Katz did not expose his telephone conversation to the public. To

the contrary, he occupied a telephone booth, shut the door behind him, and paid to place

a call. Id. at 361 (Harlan, J., concurring). In other words, his phone conversation was

intentionally contained within the privacy of the booth. These “critical fact[s]” related to

Katz’s conduct “surely entitled” him “to assume that his conversation [was] not being

intercepted.” Id. (internal quotation mark omitted).

¶98 The same cannot be said for anyone who exposes a smell (including from

noncontraband items and lawful activity in his car) to the public. Unlike Katz, who

“sought to exclude . . . the uninvited ear” when he entered the booth and shut the door

behind him, id. at 352 (majority opinion), an individual who exposes an odor-producing

9
substance like marijuana to the public air cannot reasonably have intended to exclude the

uninvited nose. Certainly that individual has not manifested an expectation of privacy

in the public air that society is willing to accept as reasonable. Thus, the fact that a driver

may lawfully possesses marijuana in his car pursuant to Colorado law does not mean

that he must be deemed to have a reasonable expectation of privacy in the odors that

emanate from it and escape into the infinite outside air.

¶99 Two companion cases decided by the U.S. Supreme Court in 1986 are instructive.

In the first, Ciraolo, the Court held that naked-eye aerial observations of a backyard from

a low-flying airplane do not constitute a search under the Fourth Amendment. 476 U.S.

at 215. The Ciraolo Court emphasized that the challenged observations had taken place

“within public navigable airspace” and “in a physically nonintrusive manner,” as officers

trained in marijuana identification flew over Ciraolo’s house in a private plane to observe

with their naked eyes what the tall fences he had installed around his backyard blocked

from their view. Id. at 213. Similarly, here, Kilo’s sniff took place in the public airspace

and in a physically nonintrusive manner. But, importantly, McKnight was in his car,

which, as I discuss in more detail later, is significantly less protected by the Fourth

Amendment than Ciraolo’s home. And there is no evidence that McKnight took any steps

exhibiting a subjective expectation of privacy that can be compared to the tall fences

installed by Ciraolo to block the public’s view of his backyard. True, the case before us

does not involve naked-eye observations or, more appropriately, naked-nose ones;

rather, it entails an investigative tool that enhances a human sense. But as Dow Chemical

10
Co. v. United States (the second case) illustrates, the U.S. Supreme Court has found that

the government’s use of certain minimally-intrusive, sense-enhancing techniques does

not amount to a search under the Fourth Amendment.

¶100 In Dow Chemical, the Court held that the use of a sophisticated precision mapping

camera to obtain enhanced aerial photographs of an industrial complex from lawfully

navigable airspace is not a search prohibited by the Fourth Amendment. 476 U.S. 227,

229, 239 (1986).3 The Court acknowledged that the warrantless “surveillance of private

property by using highly sophisticated surveillance equipment not generally available to

the public, such as satellite technology,” may well be unconstitutional. Id. at 238. But the

Court determined that “[t]he mere fact that human vision [was] enhanced somewhat, at

3 The Dow Chemical Court appeared to downplay the technology employed by the
government: “Any person with an airplane and an aerial camera could readily duplicate”
the photographs taken. 476 U.S. at 231. Even overlooking the very real challenge for
“[a]ny person” to obtain and fly an airplane, the aircraft used was of a specific type that
enabled it “to provide photographic stability, fast mobility and flight endurance required
for precision photography.” Id. at 242 n.4 (Powell, J., concurring in part and dissenting
in part) (quotation omitted). Additionally, the camera used “cost in excess of $22,000.00”
in the 1980s and was described by its manufacturer “as the finest precision aerial camera
available.” Id. (quotation omitted). It was “mounted to the floor inside the aircraft and
was capable of taking several photographs in precise and rapid succession,” a technique
which “facilitate[d] stereoscopic examination” and “permit[ted] depth perception.” Id.
(quotation omitted). And some of the photographs were “capable of enlargement to a
scale of 1 inch equals 20 feet or greater, without significant loss of detail or resolution,”
thereby making it “possible to discern equipment, pipes, and power lines as small as ½
inch in diameter.” Id. at 243 (emphasis and quotation omitted). In short, the camera
mounted in the airplane “saw a great deal more than the human eye could ever see, even if the
observer was located directly above the facility.” Id. (emphasis added and quotation
omitted).
11
least to the degree” involved there, did not “give rise to constitutional problems” because

the enhanced photographs, although providing the government much more detailed

information than naked-eye views, were “not so revealing of intimate details as to raise

constitutional concerns.” Id. The Court distinguished the challenged activity from the

use of electronic equipment that would penetrate walls or windows and allow the

government to hear and record confidential discussions inside the plant regarding

chemical formulae or other trade secrets; the latter “would raise very different and far

more serious questions.” Id. at 239.4

¶101 Just as the magnifying aerial camera in the plane in Dow Chemical allowed officers

to discern objects that they could not observe with their naked eyes, Kilo’s sniff allowed

officers to discern odors in the public air outside McKnight’s car that they could not smell

with their naked noses. Further, like the technique employed in Dow Chemical, Kilo’s sniff

took place in lawful airspace and did nothing more than “enhance[] somewhat” a human

sense—smell instead of sight—without revealing such “intimate details” as to raise

constitutional concerns, see id. at 238. Kilo’s alert simply conveyed to his handler that he

4 The majority cites Dow Chemical for the proposition that “a person surely engages in
more ‘intimate activities’ in the solitary confines of his car as compared to the ‘outdoor
areas or spaces between buildings of a manufacturing plant.’” Maj. op. ¶ 45 (quoting
Dow Chemical, 476 U.S. at 236). Nowhere in Dow Chemical did the Court discuss or even
mention automobiles. Rather, the Court unsurprisingly rejected the government’s
contention that the protection afforded the curtilage area immediately surrounding a
home applied with equal force to the open areas surrounding the buildings in an
industrial plant complex. 476 U.S. at 236–39.
12
smelled the odor of at least one of five drugs, including potentially marijuana, in the

public air surrounding McKnight’s car. This is not the type of intimate detail associated

with family privacy and the home that historically has raised constitutional concerns.5

¶102 That in some situations only a sniff by a trained narcotics dog could detect the

odor of marijuana outside a car is of no moment. Other courts agree. As Judge Lewis T.

Babcock explained in United States v. Broadway, “The fact that the smell . . . [is] detected

by a dog rather than a human does not change its fundamental non-private nature.” 580

F. Supp. 2d 1179, 1191 (D. Colo. 2008); see also United States v. Roby, 122 F.3d 1120,

1124–25 (8th Cir. 1997) (“The fact that the dog, as odor detector, is more skilled than a

human does not render the dog’s sniff illegal.”); United States v. Goldstein, 635 F.2d 356,

361 (5th Cir. 1981) (“The agents’ use of a canine’s more enhanced (through training)

5 The majority compares this case to Katz, arguing that Kilo has spent “countless hours”
in training to detect the odor of marijuana and “can even alert” to a substance inside a
car contained in a box that is closed and “sealed off with duct tape.” Maj. op. ¶ 46. But
this case is actually more like Dow Chemical than Katz. In Katz, the government used an
electronic device to listen in on a private conversation that may well have included the
types of intimate details warranting Fourth Amendment protection. 389 U.S. at 348.
Consistent with Katz, in Dow Chemical, the Court cautioned that, had the government
used electronic equipment to listen in on conversations inside the plant that may well
have included confidential details, its conduct would have raised “far more serious
questions.” 476 U.S. at 239. Here, the government used a narcotics dog to sniff odors
floating in the public air outside a lawfully stopped vehicle. This is akin to the
government’s use of a sense-enhancing, high-tech camera mounted inside a specialized
airplane flown in public, navigable airspace to observe things outside the buildings of an
industrial plant that could not be discerned with the naked eye.

13
olfactory sense cannot convert a sniff of the exterior of . . . suitcases into a search.”). Once

the odor of marijuana becomes intermingled with the public airspace, it cannot be

deemed private, and anyone who exposes such odor to the public airspace cannot claim

to have a reasonable expectation of privacy in it. “Just as evidence in the plain view of

officers may be searched without a warrant, evidence in the plain smell may be detected

without a warrant.” Roby, 122 F.3d at 1125 (internal citation omitted).

¶103 I am concerned that my colleagues in the majority bypass the critical issue related

to the location of the sniff, choosing instead to turn a blind eye to the elephant in the

room. Equally concerning, the authority on which they lean cannot hold up to scrutiny.

Other than the unjustified inference from Caballes and the ill-suited comparison to Kyllo,

both of which I address later, the majority relies on: (1) a statement we made thirty-three

years ago in People v. Unruh, 713 P.2d 370, 376 (Colo. 1986), abrogated by Esparza, ¶ 11, 272

P.3d at 370, which actually confirms my point: “[A] small minority of courts[] have

characterized a dog sniff as a search”;6 (2) the concurring opinion in a case from the

United States Court of Appeals for the Second Circuit from forty-four years ago, which

disagreed with the conclusion that case’s majority reached—“that use of a

marijuana-sniffing dog to ascertain the contents of a private bag amounts to . . . ‘plain

6All seven of the cases cited in Unruh in support of the quoted proposition are from more
than thirty years ago; more importantly, one was vacated, another was overruled, and
two were subsequently called into doubt. 713 P.2d at 376 n.9. Two additional cases
involved dog sniffs of “the persons of school students” and are distinguishable. Id.
(emphasis added).
14
smell,’” which is “comparable to a ‘plain view’” and is not a search, see United States v.

Bronstein, 521 F.2d 459, 464 (2d Cir. 1975) (Mansfield, J., concurring); and (3) a passing

observation by Justice Souter in a footnote in his dissenting opinion in Caballes. Respectfully,

this brittle foundation cannot bear the weight the majority stacks on top of it.

¶104 Significantly, I am by no means alone in concluding that there is no reasonable

expectation of privacy in odors in the public airspace that emanate from inside a lawfully

stopped car and are detected by a narcotics dog. To the contrary, I am in the company of

the great bulk of courts that have addressed this issue. See, e.g., Hearn v. Bd. of Pub. Ed.,

191 F.3d 1329, 1332 (11th Cir. 1999) (“[T]he [U.S.] Constitution does not provide Hearn

with any expectation of priva

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Source: Frix Law Library, https://www.frixlaw.com/law-library/cases/4398697. Public record. Not legal advice.