Petition for Writ of Certiorari — Sylvia Olivas, aka Sylvia Lee Gavaldon, Petitioner v. United States

______________________________________

No. ________________________

______________________________________

IN THE

SUPREME COURT OF THE UNITED STATES

_____________________________________

SYLVIA OLIVAS, PETITIONER,

vs.

UNITED STATES, RESPONDENT.

__________________________

ON WRIT OF CERTIORARI

TO THE UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

___________________________

PETITION FOR WRIT OF CERTIORARI

______________________________________

CARLTON F. GUNN

Attorney at Law

1751 Colorado Blvd., #384

Los Angeles, California 90041

Attorney for the Petitioner

QUESTION PRESENTED

A witness who testifies as a lay witness offering either factual testimony

and/or lay opinion testimony and also testifies as an expert offering expert

opinion testimony provides what is known as “dual role testimony.” The

question presented is:

Must a district court exercising its “gatekeeping role” under Rule

702 of the Federal Rules of Evidence in some instances exclude dual

role testimony under Rule 702 as not helpful to the trier of fact and/or

under Rule 403 as evidence whose probative value is outweighed by its

prejudicial effect in misleading and confusing the jury?

i

RELATED PROCEEDINGS

United States v. Olivas, No. 20-50182, 150 F.4th 1107/2025 WL

2437635 (9th Cir. Aug. 25, 2025)

United States v. Olivas, No. 2:16-cr-00390-DSF (C.D. Cal. 2016)

ii

TABLE OF CONTENTS

PAGE

OPINIONS BELOW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

JURISDICTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

STATUTORY PROVISIONS INVOLVED.. . . . . . . . . . . . . . . . . . . . . . . . . 2

INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

STATEMENT OF THE CASE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

A.

TRIAL... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

B.

APPEAL.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

REASONS FOR GRANTING THE PETITION.. . . . . . . . . . . . . . . . . . . . . 7

A.

THE ADMISSIBILITY OF DUAL ROLE TESTIMONY AND

THE LIMITS ON ITS ADMISSIBILITY ARE IMPORTANT

ISSUES THIS COURT SHOULD CONSIDER.. . . . . . . . . . . . . . 7

B.

THE COURT SHOULD GRANT THE PETITION TO CLARIFY

HOW THE RULES OF EVIDENCE GOVERNING EXPERT

TESTIMONY AND IRRELEVANT AND/OR UNDULY

PREJUDICIAL EVIDENCE LIMIT DUAL ROLE

TESTIMONY.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

C.

THIS CASE IS AN EXCELLENT VEHICLE FOR

ILLUSTRATING THE LIMITS THAT SHOULD BE PLACED

ON DUAL ROLE TESTIMONY.. . . . . . . . . . . . . . . . . . . . . . . . 12

CONCLUSION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

APPENDIX 1 (court of appeals opinion and memorandum). . . . . . . . . . . . A001

APPENDIX 2 (order denying petition for rehearing en banc). . . . . . . . . . . A027

APPENDIX 3 (dual role testimony). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A028

iii

TABLE OF AUTHORITIES

CASES

PAGE

Diaz v. United States,

602 U.S. 526 (2024).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . passim

Kumho Tire Co., Ltd., v. Carmichael,

526 U.S. 137 (1999).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Olivas v. United States,

144 S. Ct. 2711 (2024).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

United States v. Baptiste,

596 F.3d 214 (4th Cir. 2010). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

United States v. Barrow,

400 F.3d 109 (2d Cir. 2005). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Brown,

776 F.2d 397 (2d Cir. 1985). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Dukagjini,

326 F.3d 45 (2d Cir. 2003). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . passim

United States v. Freeman,

498 F.3d 893 (9th Cir. 2007). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . passim

United States v. Flores-de-Jesus,

569 F.3d 8 (1st Cir. 2009). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

United States v. Haines,

803 F.3d 713 (5th Cir. 2015). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 9

United States v. Jett,

908 F.3d 252 (7th Cir. 2018). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Lopez-Medina,

461 F.3d 724 (6th Cir. 2006). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 12

United States v. Moralez,

808 F.3d 362 (8th Cir. 2015). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 9, 12

iv

TABLE OF AUTHORITIES (cont’d)

CASES (cont’d)

PAGE

United States v. Olivas,

No. 20-50182, 2023 WL 4105308 (9th Cir. June 21, 2023)

(unpublished). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 7

United States v. Perry,

14 F.4th 1253 (11th Cir. 2021). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

United States v. Rios,

830 F.3d 403 (6th Cir. 2016). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Sandoval,

6 F.4th 63 (1st Cir. 2021). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 12

United States v. Sandoval,

680 Fed. Appx. 713 (10th Cir. 2017) (unpublished). . . . . . . . . . . . . 8, 12

United States v. Simmons,

923 F.2d 934 (2d Cir. 1991). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

United States v. Thomas,

970 F.3d 809 (7th Cir. 2020). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

United States v. Thomas,

74 F.3d 676 (6th Cir. 1996). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Tocco,

200 F.3d 401 (6th Cir. 2000). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

United States v. Vera,

770 F.3d 1232 (9th Cir. 2014). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

United States v. York,

572 F.3d 415 (7th Cir. 2009). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

STATUTES AND RULES

Rule 401, Federal Rules of Evidence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Rule 402, Federal Rules of Evidence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

v

TABLE OF AUTHORITIES (cont’d)

STATUTES AND RULES (cont’d)

PAGE

Rule 403, Federal Rules of Evidence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . passim

Rule 702, Federal Rules of Evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . passim

Rule 704, Federal Rules of Evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 7, 10

OTHER AUTHORITIES

Transcript of Oral Argument, United States v. Diaz, 144 S. Ct. 1727 (2024)

(No. 23-14).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

vi

_____________________________________

PETITION FOR A WRIT OF CERTIORARI

TO THE UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

_____________________________________

Sylvia Olivas respectfully petitions for a writ of certiorari to review the

judgment of the United States Court of Appeals for the Ninth Circuit in her

case.

OPINIONS BELOW

The published opinion and accompanying unpublished memorandum

disposition of the United States Court of Appeals for the Ninth Circuit are

included in the appendix as Appendix 1 and are also available at 150 F.4th

1107 and 2025 WL 2437635. An order denying en banc review is included in

the appendix as Appendix 2. The relevant proceedings in the district court are

unpublished.

JURISDICTION

The panel decision of the court of appeals was filed on August 25, 2025.

See App. A001. A timely petition for rehearing was denied on October 1,

2025. See App. A027. This Court has jurisdiction under 28 U.S.C. § 1254(1).

1

STATUTORY PROVISIONS INVOLVED

Rule 702 of the Federal Rules of Evidence provides in pertinent part:

A witness who is qualified as an expert by knowledge,

skill, experience, training, or education may testify in the

form of an opinion or otherwise if the proponent

demonstrates to the court that it is more likely than not that:

(a) the expert's scientific, technical, or other

specialized knowledge will help the trier of fact to

understand the evidence or to determine a fact in

issue;

...

Rule 403 of the Federal Rules of Evidence provides in pertinent part:

The court may exclude relevant evidence if its probative

value is substantially outweighed by a danger of one or

more of the following: unfair prejudice, confusing the

issues, misleading the jury, undue delay, wasting time, or

needlessly presenting cumulative evidence.

INTRODUCTION

The admissibility of dual role testimony and the limits on the

admissibility of such testimony have become important issues for this Court to

consider. Over the past two decades, more and more of the circuits have

recognized such testimony raises serious concerns. Those include giving the

witness’s lay testimony unmerited credibility; inhibiting cross-examination; an

enhanced likelihood of straying from the restrictions on expert testimony; juror

confusion arising out of difficulty in discerning which testimony is lay

testimony and which testimony is expert testimony; and impermissibly

conveying hearsay when the expert strays from the scope of his expertise.

The courts of appeals have stated only that dual role testimony is not

2

“categorically prohibited,” which suggests it is prohibited in some instances.

Justice Jackson and Justice Gorsuch, in concurring opinions in this Court’s

recent decision in Diaz v. United States, 602 U.S. 526 (2024), which involved

an evidentiary rule limiting expert testimony about mental state, pointed out

the importance of more general evidentiary rules, including Rule 702’s

requirement that expert testimony be helpful to the jury and Rule 403’s

requirement that the probative value of evidence not be outweighed by its

prejudicial effect. Those rules’ concerns are also implicated by dual role

testimony, as recognized by court of appeals opinions urging caution in

allowing such testimony. Of particular concern is a risk jurors may infer the

expert opinion is supported by knowledge of the defendant that is not in

evidence at trial.

This case is an excellent vehicle for illustrating when such testimony is

prohibited. The dual role testimony offered by the witness here, Rene Enriquez

– who not only testified as an expert, but had an intimate relationship with the

leader of the conspiracy in which Ms. Olivas allegedly participated, David

Galvadon – is replete with examples of instances in which jurors might infer

he had other knowledge supporting his opinions. This case thus provides a

perfect opportunity to illustrate when dual role testimony should be barred.

STATEMENT OF THE CASE

A.

TRIAL.

Ms. Olivas was charged in a multi-defendant case under the Racketeer

3

Influenced and Corrupt Organizations Act (“RICO”). See Dist. Ct. Dkt. 1309.1

The racketeering enterprise was a street gang controlled by a Mexican Mafia

member named David Galvadon. See Dist. Ct. Dkt. 1309, at 3-10. The charges

against Ms. Olivas were RICO conspiracy, drug conspiracy, and money

laundering conspiracy. See Dist. Ct. Dkt. 1309, at 11, 12, 152.

The evidence included recordings of prison visits and phone calls,

correspondence, and records showing Ms. Olivas had sent $1350 to David

Galvadon over 10 years. See Dkt. 25, at 5, 7, 8, 10. The government’s theory

about Ms. Olivas, who is David Galvadon’s oldest sister, was “that Sylvia

Olivas was a trusted secretary to her brother, . . . a made Mexican Mafia

member.” ROA 75. She allegedly passed messages to and from David

Galvadon and forwarded proceeds from criminal activities. See ROA 79-80.

The defense theory was that Ms. Olivas visited David Galvadon because she

was his older sister and loved him despite his crimes. Dkt. 25, at 48. For the

same reason, she sent him – and others when he asked her – small amounts of

money. Id. She was acting not with criminal intent, but because David

Galvadon was her brother. Id.

One government witness was a former Mexican Mafia member named

Rene Enriquez. See App. A032. He was a “made” Mexican Mafia member for

17 years, App. A032, until he defected and started helping law enforcement,

App. A035, A081-85. He described the Mexican Mafia as “a very secretive

1

“Dist. Ct. Dkt.” refers to the docket in United States v. Olivas, No.

2:16-cr-00390-DSF (C.D. Cal. 2016). “Dkt.” refers to the docket in United

States v. Olivas, No. 20-50182 (9th Cir. 2020). “ROA” refers to the Excerpts

of Record in the record on appeal in the Ninth Circuit, which are filed at

Docket Entry 26.

4

and exclusive organization,” App. A038, and also described what can be fairly

described as an intimate involvement with David Galvadon. They were both

“made” at Folsom State Prison in 1985, App. A036, so they were “carnals,” or

“brothers,” App. A092. Enriquez was subsequently at Pelican Bay State Prison

with David Galvadon. App. A039. One of several people he had killed was

David Galvadon’s sister-in-law, App. A071, but that did not stand in the way

of their brotherhood. As further described infra p. 13, they “touched pinkies”

and agreed “it was business.” App. A075.

Enriquez also provided expert testimony. He interpreted recorded

conversations in which Ms. Olivas participated or which were allegedly about

her, see App. A134-75, and also interpreted correspondence, see App. A13334, 175-82. He also testified about Mexican Mafia “secretaries,” explaining a

“secretary” is “right under a Mexican Mafia member,” is “the individual who

communicates with the Mexican Mafia member,” and “controls” the “crew”

and “the money.” App. A097-98. When the prosecutor asked Enriquez how

much secretaries know about the activities of the “crew,” he answered:

“Everything. Everything goes through them.” App. A127. He then opined Ms.

Olivas was a “secretary,” App. A140, A155, A182-83, who was “passing

messages regarding Mexican Mafia business,” receiving money from David

Galvadon’s “crew,” and “also ordering edicts for the crew,” App. A182.

B.

APPEAL.

Ms. Olivas was convicted and appealed. One of her claims was that

Enriquez should not have been allowed to give both lay testimony and expert

5

opinion testimony, which the Ninth Circuit and other circuits have labeled

“dual role testimony,” United States v. Freeman, 498 F.3d 893, 903 (9th Cir.

2007). A second claim was that the testimony “secretaries” know “everything”

and Ms. Olivas was a “secretary” violated Federal Rule of Evidence 704(b)’s

prohibition on ultimate issue opinions about mental states constituting

elements of crimes. As to the dual role testimony claim, the defense pointed to

concerns courts have expressed about such testimony; noted the Ninth Circuit

has held only that such testimony is not “categorically prohibited,” Freeman,

498 F.3d at 904, and this suggests it is prohibited in some cases; and argued

this was a case where the testimony should have been prohibited. See Dkt. 25,

at 19-28. As to the Rule 704(b) claim, the defense argued the testimony

“secretaries” know “everything” and Ms. Olivas was a “secretary” violated the

rule because it necessarily implied her mental state. See Dkt. 25, at 33-34.

A Ninth Circuit panel rejected Ms. Olivas’s appeal and affirmed, in a

memorandum filed June 21, 2023. As to the dual role testimony, it held

“Enriquez’s previous involvement with [David Galvadon] did not warrant

exclusion.” United States v. Olivas, No. 20-50182, 2023 WL 4105308, at *2

(9th Cir. June 21, 2023) (unpublished). As to the Rule 704(b) claim, it pointed

to prior Ninth Circuit cases allowing such testimony and held it did not

necessarily imply the ultimate conclusion about mental state. Id.

The defense filed a petition for writ of certiorari that raised the Rule

704(b) claim and pointed to another case raising a comparable claim in which

this Court had just granted review. After the Court decided the other case –

Diaz v. United States, 602 U.S. 526 (2024) – the Court vacated and remanded

this case for further consideration in light of Diaz. See Olivas v. United States,

6

144 S. Ct. 2711 (2024). But a Ninth Circuit panel affirmed again. It addressed

the Rule 704(b) claim in a lengthy published opinion, in which it

acknowledged there might have been error under Diaz, but held, first, any

error was not plain and, second, it had not affected Ms. Olivas’s substantial

rights even if it was plain. See App. A001-19. It addressed the remaining

defense claims in an accompanying memorandum. See App. A020-26. Its

disposition of the dual role testimony claim exactly tracked the prior

memorandum. Compare App. A021-22 with United States v. Olivas, 2023 WL

4105308, at *2.

The defense thereafter filed a petition for rehearing en banc, seeking en

banc review of the dual testimony issue and an unrelated instructional issue.

See Dkt. 105. The petition was denied without comment.

REASONS FOR GRANTING THE PETITION

A.

THE ADMISSIBILITY OF DUAL ROLE TESTIMONY AND THE

LIMITS ON ITS ADMISSIBILITY ARE IMPORTANT ISSUES THIS

COURT SHOULD CONSIDER.

In the last two decades, dual role testimony – in which the witness gives

both lay testimony and expert opinion testimony – has evolved as an

evidentiary issue and become more and more important. One of the first courts

to flag it as an issue was the Second Circuit in United States v. Dukagjini, 326

F.3d 45 (2d Cir. 2003). See id. at 53-56. And multiple other circuits have

flagged it as a serious issue since Dukagjini. Those include at least the First,

7

Fourth, Fifth, Sixth, Seventh, Eighth, Ninth, Tenth, and Eleventh Circuits. See

United States v. Perry, 14 F.4th 1253, 1265 (11th Cir. 2021); United States v.

Sandoval, 6 F.4th 63, 86 (1st Cir. 2021); United States v. Sandoval, 680 Fed.

Appx. 713, 718 (10th Cir. 2017) (unpublished); United States v. Moralez, 808

F.3d 362, 365-66 (8th Cir. 2015); United States v. Haines, 803 F.3d 713, 73031 (5th Cir. 2015); United States v. Baptiste, 596 F.3d 214, 224 (4th Cir.

2010); United States v. York, 572 F.3d 415, 425 (7th Cir. 2009); United States

v. Freeman, 498 F.3d 893, 904 (9th Cir. 2007); United States v. LopezMedina, 461 F.3d 724, 743 (6th Cir. 2006).

The courts of appeals also have recognized this sort of testimony raises

serious concerns. The Second Circuit in Dukagjini spoke of “the heightened

risk” posed by such testimony. Id., 326 F.3d at 56. See also Sandoval, 680 Fed.

Appx. at 718 (noting testimony “may present special risks” and going on to

discuss Dukagjini and other cases). The Ninth Circuit spoke of the “dangers”

of such testimony and “share[d] the concerns expressed by the Second Circuit

in Dukagjini.” Freeman, 498 F.3d at 903. See also York, 572 F.3d at 425

(recognizing “inherent dangers with this kind of dual testimony” and citing,

inter alia, Dukagjini). Other courts have spoken of “the care,” United States v.

Thomas, 970 F.3d 809, 814 (7th Cir. 2020), and “special precautions,” Perry,

14 F.4th at 1265, district courts must take, and warned that “courts must be

mindful,” Sandoval, 6 F.4th at 86 (quoting United States v. Flores-de-Jesus,

569 F.3d 8, 21 (1st Cir. 2009)).

The risks and the dangers created are at least five. First, “by qualifying

as an ‘expert,’ the witness attains unmerited credibility when testifying about

factual matters from first-hand knowledge.” Freeman, 498 F.3d at 903

8

(quoting Dukagjini, 326 F.3d at 53). Second, “expert testimony by a fact

witness or case agent can inhibit cross-examination . . . [because a] failed

effort to impeach the witness as expert may effectively enhance his credibility

as a fact witness.” Freeman, 498 F.3d at 903 (quoting Dukagjini, 326 F.3d at

53-54). Third, “there is an increased danger that the expert testimony will stray

from applying reliable methodology and convey to the jury the witness’s

sweeping conclusions about [defendants’] activities, deviating from the

strictures of Rules 403 and 702.” Freeman, 498 F.3d at 903 (quoting

Dukagjini, 326 F.3d at 54, and United States v. Simmons, 923 F.2d 934, 94647 n.5 (2d Cir. 1991)). Fourth, there is a risk of juror confusion because

“[s]ome jurors will find it difficult to discern whether the witness is relying

properly on his general experience and reliable methodology, or improperly on

what he has learned [through personal knowledge].” Freeman, 498 F.3d at 903

(quoting Dukagjini, 326 F.3d at 54). Fifth, “when [an expert] strays from the

scope of his expertise, he may impermissibly rely upon and convey hearsay

evidence.” Freeman, 498 F.3d at 903 (quoting Dukagjini, 326 F.3d at 55). See

also Moralez, 808 F.3d at 365 (listing same concerns); Haines, 803 F.3d at

730-31 (quoting Dukagjini’s concerns).

B.

THE COURT SHOULD GRANT THE PETITION TO CLARIFY HOW

THE RULES OF EVIDENCE GOVERNING EXPERT TESTIMONY AND

IRRELEVANT AND/OR UNDULY PREJUDICIAL EVIDENCE LIMIT

DUAL ROLE TESTIMONY.

This Court recently considered a different aspect of expert opinion

9

testimony – the limitations created by Rule 704(b) of the Federal Rules of

Evidence – in Diaz v. United States, 602 U.S. 526 (2024). Rule 704 generally

allows expert opinion testimony on “ultimate issue[s],” Fed. R. Evid. 704(a),

but prohibits them when the issue is “whether the defendant did or did not

have a mental state or condition that constitutes an element of the crime

charged or of a defense,” Fed. R. Evid. 704(b). The specific issue presented in

Diaz was whether an opinion about “most” drug couriers’ knowledge was

barred by Rule 704(b). The court held it was not barred because an opinion

about “most” drug couriers’ knowledge was not an opinion about all drug

couriers and so not an opinion about a particular defendant in a particular case.

See Diaz, 602 U.S. at 528, 535-36.

The focus of the majority opinion in Diaz was solely on Rule 704(b)’s

limit on ultimate opinion testimony, as that was the question presented, see id.

at 528. But both a concurring opinion by Justice Jackson and a dissenting

opinion by Justice Gorsuch pointed out the importance of other rules. Justice

Jackson, while “join[ing] the Court’s opinion,” spoke generally of “other

Rules of Evidence that might require exclusion,” including “those that guard

against irrelevant or unduly prejudicial testimony,” and pointed to Rules 401,

402, 403, and 702. See id. at 541-42 (Jackson, J., concurring). And Justice

Gorsuch also pointed to those rules. First, he pointed to the rules of relevance,

including Rule 403, which “stands as another bulwark,” and “permits courts to

‘exclude relevant evidence’ when its ‘probative value is substantially

outweighed by a danger of . . . unfair prejudice.’” Id. at 553 (Gorsuch, J.,

dissenting) (quoting Fed. R. Evid. 403). Second, he “[a]dd[ed] to those rules at

least one more,” noting the “gatekeeping” requirement that was extended to

10

non-scientific testimony in Kumho Tire Co., Ltd., v. Carmichael, 526 U.S. 137

(1999), and codified in Rule 702. Diaz, 602 U.S. at 554 (Gorsuch, J.,

dissenting). And the majority opinion said nothing to reject Justice Jackson’s

and Justice Gorsuch’s suggestion of these other rules’ significance. Indeed,

two members of the majority suggested some of the same rules during oral

argument. Transcript of Oral Argument at 22-23, 35-36, 98-99, United States

v. Diaz, 144 S. Ct. 1727 (2024) (No. 23-14).

These rules’ concerns are implicated by dual role testimony just as they

are by ultimate issue testimony. The Ninth Circuit’s Freeman opinion warns

courts must “engage[ ] in vigilant gatekeeping.” Id., 498 F.3d at 904. While

Freeman did not describe exactly which aspect of the Rule 702 requirements

about which courts must be vigilant, one of those requirements, quoted by

Justice Gorsuch in Diaz, is that the testimony “assist the trier of fact to

understand the evidence.” Diaz, 602 U.S. at 554 (Gorsuch, J., dissenting)

(quoting Kumho Tire and Fed. R. Evid. 702(a) (1999)).

Freeman and Dukagjini, which Freeman extensively quoted, also point

to related Rule 403 concerns. Those include a “risk of prejudice because the

jury may infer that the agent’s opinion about the criminal nature of the

defendant’s activity is based on knowledge of the defendant beyond the

evidence at trial.” Dukagjini, 326 F.3d at 53 (cleaned up). They also include

“another concern under Rule 403, juror confusion,” because “[s]ome jurors

will find it difficult to discern whether the witness is relying properly on his

experience and reliable methodology, or improperly on [his lay knowledge].”

Freeman, 498 F.3d at 903 (quoting Dukagjini, 326 F.3d at 54). Related to

these concerns – and of particular concern in the present case, see infra pp. 1411

17 – is that jurors “may unduly credit the opinion testimony due to a

perception that the expert was privy to facts . . . not presented at trial.” United

States v. Jett, 908 F.3d 252, 267 (7th Cir. 2018) (cleaned up). See also United

States v. Rios, 830 F.3d 403, 414 (6th Cir. 2016) (same); United States v.

Brown, 776 F.2d 397, 401 n.6 (2d Cir. 1985) (recognizing risk jury may infer

opinion “based on [expert’s] knowledge of the defendant beyond the evidence

at trial”). These dangers also go to the Rule 702 question of whether the expert

testimony will “assist the trier of fact,” because creating confusion in jurors

and/or leading them to unduly credit expert testimony based on an improper

perception does not assist them but makes their job more difficult.

C.

THIS CASE IS AN EXCELLENT VEHICLE FOR ILLUSTRATING

THE LIMITS THAT SHOULD BE PLACED ON DUAL ROLE

TESTIMONY.

In holding dual role testimony inadmissible, the courts of appeals have

said generally that dual role testimony is not “categorically prohibited,” United

States v. Moralez, 808 F.3d at 366; Freeman, 498 F.3d at 904; United States v.

Lopez-Medina, 461 F.3d at 742; United States v. Barrow, 400 F.3d 109, 124

(2d Cir. 2005), or not “per se prohibite[d],” Rios, 830 F.3d at 414 (quoting

United States v. Tocco, 200 F.3d 401, 418 (6th Cir. 2000), and United States v.

Thomas, 74 F.3d 676, 682 (6th Cir. 1996)); see also United States v. Sandoval,

6 F.4th at 86; United States v. Sandoval, 680 Fed. Appx. at 718. But the

negative pregnant of “categorically” is that such testimony should be

prohibited in some cases. Ms. Olivas’s case provides an opportunity to

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illustrate how and where the line should be drawn. And it should be drawn to

preclude the dual role testimony in Ms. Olivas’s case.

This is because of key differences between the present case and the

typical case. In the typical case, the dual role witness is a law enforcement

agent whose lay knowledge arises only from his involvement as an objective

investigator. See, e.g., Sandoval, 6 F.4th at 85-86; Moralez, 808 F.3d at 365;

Freeman, 498 F.3d at 898; Lopez-Medina, 461 F.3d at 742; Dukagjini, 326

F.3d at 49-50. Here, in contrast, the witness’s lay knowledge arose from an

intimate relationship with the person whose communications and “crew” he

was opining about. Rene Enriquez and David Galvadon were “made” members

of the “very secretive and exclusive” Mexican Mafia, whose members are

“carnals,” or “brothers.” Supra pp. 4-5. The two men were “made” together in

1985, as evidenced by both Enriquez’s testimony and a group photo of this

1985 “class.” See App. A042-43. Enriquez and David Galvadon were in

Folsom State Prison together and then in Pelican Bay State Prison together.

They were such “brothers” that Enriquez could murder David Galvadon’s

sister-in-law and be absolutely forgiven. As Enriquez testified:

I asked Mr. Galvadon if he had a problem with what

happened to Cynthia; and he said: No, not at all. He was

cool with it. . . .

And he said: No, there was no problem and he

understands it was business and that’s all it was; and we

shook pinkies through the little hole.

You can’t shake hands but there’s these little ports in

the things so we touched pinkies. That’s where you shake

hands. So we touched pinkies.

And it was resolved at that point. There was no

organizational repercussion for her murder. Her husband

agreed to it and her brother-in-law who was the Mexican

Mafia member subsequently agreed that it was okay.

App. A075.

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This intimate relationship triggers the dual role testimony concern that

jurors “may unduly credit the opinion testimony due to a perception that the

expert was privy to facts about the defendant not presented at trial,” supra p.

12. Anytime the jury heard one of Enriquez’s expert opinions, it knew he also

had intimate personal involvement with David Galvadon and his Mexican

Mafia activities. It knew they had been “made” at the same time and had been

in the same prisons for years. It knew they were close enough that Enriquez

could murder David Galvadon’s sister-in-law and “it was okay” because they

“touched pinkies.”

Examples of how this could have infected the jury’s evaluation of

Enriquez’s testimony abound in his specific opinions about conversations and

correspondence.

•

An opinion that a man named Jose Loza was David Galvadon’s

“shot caller” and about the meaning of a telephone conversation

in which Loza participated, based on “my knowledge of the

Mexican Mafia first,” App. A113, but also what David Galvadon

“in his mind thinks,” App. A114. Was Enriquez’s opinion of what

David Galvadon “in his mind thinks” based solely on his

expertise or also on his intimate relationship with David

Galvadon?

•

An opinion that a “Lora” referred to in one of Ms. Olivas’s letters

to David Galvadon is a gang associate and that “Lora’s sister,

Jessica,” in the letter referred not to a sister but a brother named

Jesse Hernandez. See App. A133-34. Was Enriquez’s opinion

about this based in part on outside knowledge he had about the

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gang and Lora and Jesse?

•

An opinion that conversation between David Galvadon and Ms.

Olivas during a July 14, 2007 jail visit about “Bryan” using an

“iron fist” and being too harsh was David Galvadon grooming

“Bryan” to be a “shot caller.” See App. A135-36. Was this based

in part on outside knowledge about David Galvadon’s “shot

callers” and/or David Galvadon’s feelings about “iron fist[s]” and

being harsh?

•

An opinion that another part of the conversation during the July

14, 2007 visit was about “turning [David Galvadon’s son’s

girlfriend] away for tax collection.” App. A141. Here, Enriquez

actually admitted it was based on “my past knowledge of the

Galvadon family, David Galvadon, and his son.”App. A141.

•

An opinion that an individual discussed during a June 23, 2013

visit was another associate whom David Galvadon wanted taken

care of in prison. See App. A150. Was this also based in part on

Enriquez’s personal understanding of David Galvadon and his

crew and David Galvadon’s attitude about taking care of crew

members?

•

Opinions about references to “Lora” and “Julie” in letters from

Ms. Olivas to David Galvadon and a recorded prison call to Ms.

Olivas from another of her brothers, Roy Galvadon, Sr. See App.

A154-55, A157, A159. Was this based in part on a personal

understanding of David Galvadon and his crew, or possibly

specific understandings about “Lora” and “Julie”?

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•

An opinion Ms. Olivas was suggesting “informal gang code”

when an undercover informant met with her. See App. A162. Was

this based not only on expertise, but also a belief based on his

relationship with David Galvadon about what “informal gang

code” David Galvadon used? Enriquez had testified that informal

gang code is not fixed, but “person specific.” App. A132.

•

An opinion that several letters signed “J” showed the writer was a

“shot caller” for David Galvadon. See App. A176. Was this based

on expertise or based on a personal understanding or opinions

about David Galvadon and his crew and his grooming and/or

selection of “shot callers”? This was aggravated by the complete

failure of Enriquez to give any explanation of his opinion that the

letters were written by a “shot caller,” which left even more room

for speculation about whether it might be based on something

other than his expertise, cf. United States v. Vera, 770 F.3d 1232,

1241 (9th Cir. 2014) (recognizing need for witness to “explain

how he applies his knowledge to interpret particular words and

phrases used in particular conversations” (cleaned up) (emphasis

in original)).

•

Enriquez’s concluding opinion that “[s]he’s a secretary for the

Mexican Mafia,” App. A182. Was this opinion based just on

expertise, or was it also based on opinions derived from

Enriquez’s personal relationship with David Galvadon and

resulting knowledge of David Galvadon and his family? Cf. App.

A141 (acknowledging “past knowledge of the Galvadon family”).

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The foregoing are just some examples. Throughout Enriquez’s specific

opinion testimony about David Galvadon, his crew, and Ms. Olivas, the jury

would have wondered whether his opinions were buttressed by knowledge,

understandings, and/or beliefs arising from his intimate relationship with

David Galvadon after they were “made” as “carnals” in the “secretive and

exclusive” Mexican Mafia organization.

While dual role testimony is not categorically prohibited, it should have

been prohibited in this case. This case presents a perfect opportunity to show

how and where to draw the line that the courts of appeals’ qualifier of

“categorically” suggests.

CONCLUSION

The Court should grant the Petition.

Respectfully submitted,

DATED: November 6 , 2025

s/ Carlton F. Gunn

CARLTON F. GUNN

Attorney at Law

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