Osage Nation Office of the Attorney General (2026)

Osage Nation Office of the Attorney General

Trial Court of the Osa i

Ea tee sage Nation

March 13, 2026 MAR 18 2026

OPINIONS OF THE ATTORNEY GENERAL By.

OF THE OSAGE NATION

ONAG-2026-01

QUESTIONS SUBMITTED BY: The Honorable Geoffrey M. Standing Bear, Principal

Chief of the Osage Nation.

This Office has received your request for an Official Attorney General Opinion regarding

the ownership of pore space beneath the Osage Nation reservation. To wit, you ask:

L QUESTIONS and SHORT ANSWERS.

1. Did the Act of June 28, 1906, Ch. 3572, 34 Stat. 539 (“1906 Act”), transfer title

to pore space to individual Osage allottees as part of the surface estate, or is

pore space retained as part of the Osage Mineral Estate and held in trust by

the United States for the benefit of the Osage Nation?

The 1906 Act did not transfer or convey title to pore space to individual Osage

allottees as part of the surface estate. The pore space within the Osage Reservation

remains part of the Osage Mineral Estate and is held in trust by the United States

for the benefit of the Osage Nation.

2. Is ownership of pore space within the Osage Reservation determined by the

laws of the State of Oklahoma?

No, the State of Oklahoma’s laws regarding the ownership of pore space, which

were first enacted in 2011, do not govern whether the 1906 Act transferred pore

space within the Osage Reservation to Osage allottees as part of the surface estate.

The interpretation of the 1906 Act, and the relevant treaties and subsequent federal

legislation, is determined by federal law.

Il. Introduction

On October 31, 2025, the Office of the Attorney General of the State of Oklahoma issued

Attorney General Opinion 2025-14 (“Oklahoma Opinion”), addressing whether the 1906 Act

“transfer[red] title to pore space to individual members of Osage Nation” and whether this pore

space is “governed by Oklahoma law or by a recent act of the Osage Nation Congress that purports

to make pore space part of the mineral estate.”' As used in this Opinion, “pore space” refers to

subsurface voids within and among the strata that comprise the mineral formations reserved to the

' Okla. Att'y Gen. Op. No. 2025-14 [hereinafter “Oklahoma Op.”], at | (Oct. 31, 2025).

Osage Nation, including containing chambers, voids, porosity, and spaces naturally occurring or

created by extraction or other subsurface operations.

This Opinion briefly describes the history of the Osage Reservation, then reviews the

Oklahoma Opinion, applicable statutes, case law, and instructive contemporary legal authorities.

After analyzing such materials, this Opinion concludes that Congress did not sever and convey to

individual members of the Osage Nation the pore space beneath the Osage Reservation. Those

spaces remain in trust for the benefit of the Osage Nation as an incident of its reserved mineral

estate (“Osage Mineral Estate”).

In reaching this conclusion, one must begin with the text of the 1906 Act and ask whether

Congress clearly allocated to the surface estate the right to control subsurface voids within the

mineral formations expressly reserved to the Osage Nation. All stakeholders agree that the 1906

Act is silent as to ownership of subsurface voids. But silence, of course, is not sufficient to infer

divestiture of valuable incidents of Osage Nation lands. Historical context helps provide clarity of

ownership, which is controlling regardless of any later-enacted Oklahoma law.

By 1906, a substantial body of authority had developed holding that the mineral estate—

and not the surface estate—owned caverns and voids within severed mineral formations.

Therefore, the 1906 Act’s silence on pore space cannot provide a basis for inferring its transfer to

surface-estate allottees. This is true even if the Indian canons of statutory construction (“Indian

canons”) are not applied. However, should the Indian canons be employed—a requirement where

ambiguity exists—federal ownership of pore space in trust for the Osage Nation is an inescapable

conclusion.

The Oklahoma Opinion begins from a different premise and, for that reason, reaches an

incorrect result. Rather than ask whether the 1906 Act unambiguously addresses which estate owns

the pore space, it starts by reading various sections of the 1906 Act together to assert that pore

space was included in the property rights granted to individual surface estate owners. The

Oklahoma Opinion acknowledges that the Indian canons require resolution of ambiguity in favor

of Indian tribes, but it treats the Indian canons as inoperative by characterizing the 1906 Act as

unambiguous. In so doing, the Oklahoma Opinion relies on after-the-fact Oklahoma common law

and statutory developments to supply default rules for a federal statute from 1906—an interpretive

decision that cannot establish what Congress intended for the Osage Nation before Oklahoma

statehood. Accordingly, federal law governs the question of pore space ownership within the

Osage Reservation, not Oklahoma state law.

The Oklahoma Opinion further concludes that the “term ‘other minerals’ unambiguously

does not include pore space...” That analysis assumes the conclusion by treating the absence of

explicit reservation as dispositive. In any event, it misstates the dispositive issue. The question is

not whether pore space is a mineral. Instead, it is whether Congress, in reserving for the Osage

Nation’s benefit a mineral estate, clearly severed and conveyed to the surface estate the right to

control the pore space within those reserved mineral formations.

* Id. at 6.

This Opinion clarifies the proper method to resolve the question of pore space ownership

and explains why it continues to be held in trust by the United States for the Osage Nation.

III. History of the Osage Reservation.’

Ancestors of the Osage originally occupied lands in the Ohio River valley. Beginning

nearly two thousand years ago, a great migration occurred, which ultimately led to settlement

around Cahokia Mounds near modern-day Saint Louis, Missouri. Following the introduction of

the horse in the late seventeenth century, the Osage expanded their geographic footprint, such that

by 1750, they established control over much of modern-day Arkansas, Kansas, Missouri, and

Oklahoma.

The first Osage treaty with the United States was entered into in 1808,* shortly after the

Louisiana Purchase of 1803. This treaty of “peace, friendship and intercourse” saw the cession of

approximately 50 million acres of Osage land in modern-day Arkansas and Missouri in exchange

for $1,200, annual “merchandise” deliveries valued at $1,500, and certain other benefits such as

construction of blockhouses and provision of a blacksmith.° Additional cessions of approximately

1.8 million acres of land in modern-day Arkansas and Oklahoma were made in 1818 to

accommodate Cherokee settlers who relocated from their ancestral homelands.°

In 1825, all remaining Osage lands in Missouri and modern-day Arkansas and Oklahoma—

approximately 45 million acres—were ceded to the United States in exchange for $140,000

payable over 20 years, “merchandise” valued at $6,000, “horses and equipage” valued at $2,600,

and certain other benefits such as 600 head of cattle and provision of a blacksmith. ’ This 1825

treaty also established a reservation in modern-day Kansas for the Osage, for “so long as they may

choose to occupy the same....”* In 1865, the Osage Reservation in Kansas was diminished through

the sale of approximately 850,000 acres of “surplus lands” to the United States in exchange for

$300,000, and the transfer to the United States of approximately 3.2 million acres for later sale,

the proceeds of which were to be held in “credit” for the Osage.”

In 1870, Congress authorized the sale of the diminished Osage Reservation in Kansas—

approximately four million acres—and directed that proceeds from such sale be used to provide

3 See Andrea A. Hunter, Osage Cultural History, The Osage Nation, (excerpt from Osage Nation NAGPRA Claim for

Human Remains Removed from Clarksville Mount Group (23P16), Pike County, Missouri), www.osagenationnsn.gov/who-we-are/historic-preservation/osage-cultural-history; see a/so Louis F. Burns, Osage, The Encyclopedia

of Oklahoma History and Culture, www.okhistory.org/publications/enc/entry.php?entry=OS001.

4 Treaty with the Great and Little Osage (Nov. 10, 1808), 7 Stat. 107.

5 Id., arts. 1, 3, and 6.

° Treaty with the Great and Little Osage (Sep. 25, 1818), 7 Stat. 183.

7 Treaty with the Osage (Jun. 2, 1825), arts. 1, 3-4, and 12, 7 Stat. 240. A later treaty, also in 1825, finalized

approximately two months later adjusted certain rights described in the early treaty. See Treaty with the Great and

Little Osage (Aug. 10, 1825). For completeness, an earlier treaty between the Osage and the United States in 1822

addressed issues unrelated to land cessions. See Treaty with the Great and Little Osage (Aug. 21, 1822).

*/d., art. 2. A later treaty in 1839 resolved overlapping land claims between the Osage and other tribes suc! the

Cherokee, Kansa (Kaw), Seneca, and Shawnee. In exchange for the Osage ceding title to such lands, the United States

agreed, among other things, to make payments for 20 years of $12,000 and $8,000 “in goods, stock, provisions, or

money....” See Treaty with the Great and Little Osage (Jan. 11, 1839), arts. 1-2, 7 Stat. 576.

° Treaty with the Great and Little Osage (Sep. 29, 1865), arts. 1-2, 14 Stat. 687 [hereinafter “1865 Treaty”].

the Osage a “permanent home in the Indian Territory.” '° The Osage subsequently assented to these

terms,'' and lands within the existing Cherokee Reservation were identified for purchase and

settlement.'? In 1872, Congress established the Osage Reservation within modern-day Oklahoma,

consisting of approximately 1.47 million acres at a cost to the Osage Nation of $1,099,137.41.3

As discussed more fully below, Congress in 1906 enacted legislation that “severed the

surface estate of the [Osage] Reservation from the subsurface mineral estate....”'* This severance

allowed for the allotment of surface estate lands to individual Osage and the continued reservation

of “all subsurface mineral estate in trust for the benefit of [Osage] Nation.”'> Over the past 120

years, there have been very few disputes over the scope of the reserved mineral estate, and in those

cases that have been litigated, Osage Nation interests have prevailed. '°

Recent developments that incentivize the storage of carbon dioxide gas (*CO2”) within

subsurface pore space have triggered new attempts at challenging Osage Nation ownership of pore

space within its reserved mineral formations.'’ The financial benefits associated with such

developments have led to interest from CO2 storage companies in exploiting this pore space.

Despite decades of Osage Nation-authorized pore space use by producers injecting CO2 to engage

in enhanced oil recovery, the Oklahoma Opinion now seeks to revisit the issue, primarily based on

a 2011 state law that defines pore space as belonging to the surface estate.'* For the reasons

explained below, that may be true elsewhere in Oklahoma, but not within the Osage Reservation.

IV. — Statutory interpretation and the Indian canons.

When ascertaining the meaning of a statute, we begin with the text.'? If the statute is

unambiguous, that generally concludes any analysis.”? But if the text is ambiguous, the meaning

is discerned by applying various tools of statutory interpretation. Where federal legislation

concerns Indian tribes, “the standard principles of statutory construction do not have their usual

' Act of July 15, 1870, ch. 296, § 12, 16 Stat. 335, 362 [hereinafter “1870 Relocation Act”)]. This removal to the

Indian Territory following the sale of the diminished Osage Reservation was originally contemplated in the Article

XVI of the 1865 Treaty.

"1 Osage Agreement of Sep. 10, 1870 (implementing the 1870 Relocation Act). This assent is sometimes referred to

as the Drum Creek Treaty of 1870 [hereinafter the “Drum Creek Treaty”.

"2 Cherokee Nation previously agreed in 1866 to the terms of such possible settlement. See Treaty with the Cherokee

(July 19, 1866), arts. 16, 14 Stat. 799. A quitclaim deed from Cherokee Nation to the United States was executed after

receipt of all payments owed by Cherokee Nation Principal Chief Charles Thompson on June 14, 1883.

'3 Act of June 5, 1872, ch. 310 17 Stat. 228-229. See also United States v. Cherokee Nation, 474 F.2d 628, 634 (Ct.

Cl. 1973).

"4 Letter from Tara Sweeney, Assistant Secretary - Indian Affairs, to Geoffrey Standing Bear, Principal Chief, Osage

Nation, at 26 (June 26, 2020) (describing the 1906 Act).

'S id.

'© See, e.g., Brewer-Elliott Oil & Gas Co. v. United States, 260 U.S. 77 (1922); United States v. Osage Wind, LLC,

871 F.3d 1078 (10th Cir. 2017),

'’ The first CO2 storage well in the United State was permitted in 2011 and began injecting CO2 stored from ethanol

productions in 2017. See U.S. Dep’t of Energy, Archer Daniels Midland Company ~ Illinois Industrial Carbon Capture

and Storage (ICCS) Project (project page, updated 2017).

'S 60 Okla. Stat. § 6-11 (2011).

"© BedRoc Ltd., LLC v. United States, 541 U.S. 176, 183 (2004) (citing cases) (“Thus, our inquiry begins with the

statutory text, and ends there as well if the text is unambiguous.”).

20 Iq.

force.”?! Instead, interpretation requires application of the Indian canons, which “are rooted in the

unique trust relationship between the United States and the Indians.”?? These “statutes are to be

construed liberally in favor of the Indians, with ambiguous provisions interpreted to their

benefit.””3 A corollary to this principle is that “congressional intent to extinguish Indian title must

be plain and unambiguous and will not be lightly implied.”

Courts, however, “cannot ignore plain language that,” viewed in historical context and

upon “fair appraisal,” clearly forecloses a tribe’s later claims.* The inquiry, therefore, turns on

the statutory text’s “ordinary and popular” meaning.° “Importantly, the proper inquiry focuses on

the ordinary meaning of the reservation at the time Congress enacted it.”*’ As Justice Gorsuch has

cautioned, “if judges could freely invest old statutory terms with new meanings, we would risk

amending legislation outside the single, finely wrought and exhaustively considered, procedure

the Constitution commands.”?’ Applying new meanings to terms used in the past “would risk, too,

upsetting reliance interests in the settled meaning of a statute.”?

V. Question 1: The 1906 Act does not convey pore space to Osage Nation allottees as

part of the surface estate.

Determining whether the 1906 Act conveyed title to pore space to individual Osage

allottees or instead left pore space as an incident of the Osage Mineral Estate requires careful

attention to both the Act’s text and the contemporaneous understanding of what the Act would

have been understood to convey. Accordingly, this Section examines the text of the 1906 Act and

draws on contemporaneous case law addressing mineral estates and the rights attendant to them to

illuminate how the Act would have been interpreted at the time of enactment. This section then

turns to relevant modern decisions, which further support the conclusion that pore space within

the Osage Reservation was retained by the Osage Mineral Estate.

a. The 1906 Act does not discuss whether pore space attaches to the surface

estate or the mineral estate.

As mentioned above, this Opinion first analyzes whether the 1906 Act unambiguously

severed and conveyed to surface estate owners the subsurface voids within the mineral formations

reserved to the Osage Nation, or whether those voids were left as an incident of the Osage Mineral

Estate. Beginning with the text, Section 2 of the 1906 Act set out a process to divide “all lands

belonging to” the Osage Nation “among the members of said tribe....”*”

2! Montana v. Blackfeet e of Indians, 471 U.S. 759, 766 (1985).

2 Oneida Cnty. v. Oneida Indian Nation, 470 U.S. 226, 247 (1985).

? Montana, 471 U.S. at 766 (citing McClanahan y. Arizona State Tax Comm'n, 411 U.S. 164, 174 (1973) and Choate

v. Trapp, 224 U.S. 665, 675 (1912)).

4 Oneida Cnty., 470 U.S. at 247-48 (cleaned up).

25 Oregon Dep't of Fish & Wildlife v. Klamath Indian Tribe, 473 U.S. 753, 774 (1985) (citations omitted).

°° BedRoc Ltd., LLC v, United States, 541 U.S. 176, 184 (2004) (citations omitted).

27 Id, (citations omitted) (emphasis added).

28 New Prime Inc. y. Oliveira, 586 U.S. 105, 113 (2019) (citation and internal quotation marks omitted).

29 Id.

°° 1906 Act, § 2. The “members of said tribe” are those individuals who are included on the Osage roll, which is

described more particularly in Section 1 of the 1906 Act.

The 1906 Act divided the Osage Nation’s land through a sequence whereby each member

selected three tracts of 160 acres of land, with any remaining lands “divided as equally as

practicable among said members....”>! Members were required to designate which of their three

160-acre selections would be their “homestead” and thus “inalienable and nontaxable until

otherwise provided by Act of Congress.”*? The other two selections were then designated “surplus

land,”*> which were inalienable for a period of 25 years and non-taxable for a period of three

years.*4

These conveyances were undeniably broad. For example, Section 7 of the 1906 Act stated

that these lands were set aside for—

the sole use and benefit of the individual members of the tribe entitled thereto, or

to their heirs, as herein provided; and said members, or their heirs, shall have the

right to use and to lease said lands for farming, grazing, or any other purpose not

otherwise specifically provided for herein, and said members shall have full control

of the same, including the proceeds thereof: Provided... That all leases given on

said lands for the benefit of the individual members of the tribe entitled thereto, or

for their heirs, shall be subject only to the approval of the Secretary of the Interior.*>

Despite the breadth of these surface estate conveyances, Section 7 of the 1906 Act also contains a

clear structural limitation. The clause “not otherwise specifically provided for herein” confirms

that this provision does not override the 1906 Act’s separate treatment of the Osage Mineral Estate.

Instead, it reinforces that the 1906 Act contains an equally significant reservation: “[N]othing

herein shall authorize the sale of the oil, gas, coal, or other minerals covered by said lands, said

minerals being reserved to the use of the tribe for a period of twenty-five years....”%° This

reservation period was subsequently extended, first to 1958,” then to 1984,°8 and finally to a

perpetual period of federal supervision.*? Congress in 1984 further clarified that the Osage

Mineral Estate was a trust asset, defining it as “any right, title, or interests in any oil, gas, coal, or

other mineral held by the United States in trust for the benefit of the Osage Tribe of Indians under

section 3 of the [1906 Act].*°

None of the 1906 Act nor subsequent related statutes expressly discuss ownership or

control of subsurface voids within the reserved mineral formations. Therefore, the 1906 Act is

5! Jd. at § 2(5). Certain lands within the Osage Reservation were reserved from selection. See 1906 Act, §§ 2(8)-(12).

32 Id. at § 2(4)

3d.

34 Jb, at §§ 2(4) and (7). Despite this restriction on alienability, “surplus land” could be conveyed if the Secretary of

the Interior issued the Osage allottee a “certificate of competency.” /d., at § 2(7).

Id at §7.

% Id. at § 2. See also id. at § 3 (“the oil, gas, coal, or other minerals covered by the lands for the selection and division

of which provision is herein made are hereby reserved to the Osage tribe for a period of twenty-five years from [April

8, 1906]. (extending the supervision period to 1984); Pub. L. 98-608, 98 Stat. 3163 (1984) (extending in

perpetuity supervision of the Osage Mineral Estate).

57 Act of March 2, 1929, ch. 493, 45 Stat. 1478

38 Act of June 24, 1938, 52 Stat. 1035.

®° Pub. L. 95-496, § 2(a), 92 Stat. 1660 (1978). Note that the Oklahoma Opinion incorrectly attributes the “in

perpetuity” amendment to Pub. L. No. 88-632, 78 Stat. 1008 (1964).

* Pub. L. 98-605, 98 Stat. 3163, §2(h) (1984).

ambiguous as to whether such voids were conveyed as part of the surface estate or retained as an

incident of the reserved mineral estate. The Oklahoma Opinion reaches the opposite conclusion.

It asserts, without citation to any authority, that—

pore space is not “oil, gas, coal, or other minerals covered by the lands,” but instead

is part of the surface estate, particularly given the broad power granted to individual

allottees to “use and to lease” the lands for “any ... purpose not otherwise

specifically provided” in the [1906] Act.*!

As explained below, this conclusion is inconsistent with the understanding of pore space at the

time the 1906 Act was passed and is thus incorrect.

b. Contemporanecous case law makes clear that mineral estates were commonly

understood to include subsurface voids.

Property law has long recognized the concept of split estates, which most commonly occur

where mineral interests are severed from the surface estate and conveyed to mining companies.

Disputes are not uncommon between owners of the surface estate and the mineral estate, and a

distinct body of law has therefore developed to adjudicate competing claims to subsurface voids.

In the late 1800s, courts in the United States frequently relied on English-derived principles that

recognized the mineral estate’s corporeal estate in the stratum, including the space occupied by the

minerals and the openings created by their removal. Referred to as the “English Rule,” this

common law approach has been summarized in a leading case from Kentucky discussing such

ownership as follows:

The rule in England is that in case of a grant of the minerals under land the grantee

has the exclusive right of possession of the whole space occupied by the layer

containing the minerals, and after the minerals are taken out, is entitled to the entire

and exclusive use of that space for all purposes.”

Although many states in the United States now reject the English Rule following certain

common law developments and/or the enactment of a clarifying statute, the 1906 Act’s silence

regarding pore space ownership must be evaluated through the contemporaneous understanding.

The cases discussed below are particularly instructive as to the rights and incidents of a severed

mineral estate absent an express reservation to the surface owners. To the extent such cases concern

distinguishable facts, the Indian canons resolve any ambiguity in favor of the Osage Nation. Taken

together, there is strong support to read the mineral reservation in the 1906 Act as leaving

subsurface voids within the reserved formation as an incident to the Osage Mineral Estate.

4! Oklahoma Op. at 4 (quoting 1906 Act, §§ 3,7) (alterations in original).

* Cent, Ky. Natural Gas Co. v. Smallwood, 252 $.W .2d 866, 868 (Ky. Ct. App. 1952) (referencing Bowser v. Maclean,

17 Eng.Rul. Cas. 452; Batten Pool v. Kennedy, | Ch. 256, 76 L.J.Ch.N.S. 162).

i. Lillibridge v. Lackawanna Coal Co.

In 1891, the Pennsylvania Supreme Court addressed whether “the chamber or space left by

the removal of the coal under the mining operations of the defendants” was owned by the surface

estate or the mineral estate.“ At that time, this question was described as “a novel one.’ The

Pennsylvania Supreme Court observed that plaintiff cited no authority in support of the position

that the surface estate held such title, “and it seems quite incongruous with the admitted ownership

and [mineral] estate of the defendant in the coal displaced."“°

Lillibridge provides historical context through which the 1906 Act would be understood.

After summarizing general principles of split estates, the Pennsylvania Supreme Court explained

that “‘a conveyance of the coal in fee carries everything with it, just as fully and completely as a

conveyance of the soil above.”

How [then] could the defendant own the coal absolutely and in fee-simple, and not

own the space it occupied? Or how is it possible to conceive of such a thing as the

ownership of the space independently of the coal?"

These questions could not be resolved in favor of the surface estate. Instead, “the plaintiffs, as

owners of the surface, have no right or title” to the “chamber[s]” in the mineral estate."” As such,

“[t]he right to use that space is exclusively in the [mineral estate holder], and that use is not, and

cannot be, questioned by the” surface estate.*” This historical baseline supports the conclusion that,

absent express divestiture, the United States and Osage Nation in 1906 would have understood

that a reservation of the mineral estate carried the incidents of a corporeal estate in mineral

formations, including the voids and caverns within them.*!

ii. Webber v. Vogel *

3143 Pa. 293 (1891).

"Id. at 300.

45 Id. at 301.

46 Id.

47 Id. at 302.

48 Td. at 301.

* Td. at 303.

50 Id.

5! Lillibridge’s holding is, of course, not without limits. Specifically, the Pennsylvania Supreme Court made clear

that the mineral estate owns only those pores that are “exclusively within [its] own property...” /d. at 308, This

limitation is of minimal applicability to the 1906 Act. In Lillibridge, the defendant had purchased only “all the

merchantable coal.” /d, at 299-300. The United States, on the other hand, reserved to the Osage Nation the far greater

estate of “oil, gas, coal, and other minerals.” The Supreme Court has recognized the broad reach of a reservation of

“minerals” generally. Compare Watt v. W. Nuclear, Inc., 462 U.S. 36, 53 (1983) (“we interpret the mineral reservation

in the [1916 Stock-Raising Homestead] Act to include substances that are mineral in character (i.¢., that are inorganic),

that can be removed from the soil, that can be used for commercial purposes, and that there is no reason to suppose

were intended to be included in the surface estate.”) with BedRoc Ltd., LLC v, United States, 541 U.S. 176, 183 (2004)

(“we will not extend Western Nuclear’s holding to conclude that sand and gravel are ‘valuable minerals.””). The 1906

Act is more like 1. Nuclear than BedRoc, as it has proven difficult to identify the precise contours of the Osage

Mineral Estate, making the limits imposed in Lillibridge unworkable and inapplicable. See discussion infra: United

States v. Osage Wind, LLC, 871 F.3d 1078 (10th Cir. 2017).

52 189 Pa. 156 (1899).

In 1899, the Pennsylvania Supreme Court declined to overrule Lillibridge and noted that

its holding “has become a settled rule of property in the great mining regio[n]s of the

commonwealth.” Thus, a mere seven years before the enactment of the 1906 Act, the

Pennsylvania Supreme Court confirmed that the prevailing historical understanding of pore space

ownership was that it followed the mineral estate.

Webber did, however, limit the reach of Lillibridge. The Pennsylvania Supreme Court

explained that while a “deed to the grantee” creates “an estate in fee simple in the severed coal,

and his right to the space mined out will not be distinguished from that in which the coal remains

unmined, that estate, except in very rare cases, has no badge of perpetuity.”** The written

instrument conveying the mineral estate “discloses the intention of the parties that the coal shall

be mined; that is, that the subject of the grant shall soon be exhausted or consumed.” Therefore,

Webber clarified that “while the purchaser of the coal was in good faith mining out his coal, his

right to the use of the space made vacant by his workings as they progressed could not be

successfully obstructed by the owner of the surface; and not that by the purchase of the coal he

obtained an undisputed and perpetual right of way under another’s land.°°

Notably, the constraints expressed in Webber support the view that the 1906 Act did not

convey to surface estate allottees the pore space beneath their lands. First, although the 1906 Act

initially reserved “oil, gas, coal, and other minerals” for a term of 25 years, Congress later extended

the reservation in perpetuity—confirming that the Osage Mineral Estate is not akin to a timelimited commercial grant that underlies Webber's exhaustion rationale. Relatedly, the Osage

Mineral Estate is not the result of a lessee purchasing coal from a landowner for the specified

purpose of mining and, in so doing, obtaining a determinable fee simple in the coal estate. To the

contrary, Osage allottees were allocated surface land by the United States—something even the

Oklahoma Opinion acknowledges.*’

Therefore, Webber confirms the result of Lillibridge and reinforces the conclusion that in

1906, mineral estate lessees or owners would expect to have unfettered control over pore space.

To the extent these cases purport to impose limits on the use of pore space, they are inapposite

because (1) the 1906 Act is not governed by Pennsylvania state law, and (2) the Pennsylvania

Supreme Court was discussing limitations inherent in commercial transactions where landowners

leased their mineral estate to private companies. Since that is not the case here, such limitations do

not map neatly onto a federal statutory reservation of a mineral estate held in perpetual trust.

iii. Moore v. Indian Camp Coal Co.*8

In 1907, the Ohio Supreme Court considered the question of pore space ownership. Similar

to Webber, the opinion began by acknowledging that the severance of the mineral estate from the

58 Id. at 159 (it was “not the intention of this court to overrule [Lillibridge].”).

54 Id. at 160.

53 Id.

°° Id.

57 Oklahoma Op. at 2 (“With these principles in mind, you ask whether the Osage Allotment Act (‘Osage Act’)

transferred ownership of pore space in Osage County from the United States to individual members of the Osage

Nation. As explained in Section III(A), the answer is yes.”).

58 75 Ohio St. 493 (1907).

surface estate “confers upon the owner of the mineral a fee-simple estate, which is, of course,

determinable upon the exhaustion of the mine.”°? In explaining the right of the mineral estate

owner “to use as he may choose, but without injury to the owner of the soil, the space left by

excavation of the mineral,”°° the Ohio Supreme Court held that a reversion of empty space to the

surface estate owner would be “impracticable and unjust” and “result in embarrassments to the

mining industry and would be intolerable.”°' More specifically, the Ohio Supreme Court noted

that the grantor could negotiate for limitations on pore space use, “but, in the absence of such

restrictions, we think that the rulings in [Lillibridge, Webber, and others] are sound law and should

be followed.”

Moore makes clear that, around the time of the 1906 Act, multiple states determined that

the voids in mineral estates do nor belong to the surface estate. Additionally, the Ohio Supreme

Court clarified that in the context of private mineral leasing transactions, a contrary result would

require landowners to expressly reserve their rights to caverns within the mineral estate. This

presumption supports the conclusion that the 1906 Act did not convey pore space to surface estate

allottees, as it would be “impracticable and unjust” to restrict the mineral estate without a clear

statement of intent. This is especially the case here, where the Indian canons require that the 1906

Act be liberally construed in favor of the Osage Nation.

Moore, like Lillibridge and Webber, presumes that the severance of mineral estates occurs

in commercial leasing contexts and therefore discusses incidental uses of pore space against that

backdrop. Namely, Moore held that the mineral estate “may use the space created by removal of

mineral within the grant, as a way for the carriage of minerals from his adjoining lands, or, if he

prefers to do so he may cut a passage through the minerals and use it for the carriage of minerals

from his other lands.”°? This limitation reflects the historical expectations regarding mineral

estates in 1906 and is not directly applicable to the Osage Mineral Estate, as it was not created

through leases or grants to surface estate allottees. Further, unlike the mining leases at issue in

Moore and other cases, the 1906 Act does not state a specific purpose “within the grant” (e.g., coal

extraction for so long a period as such activity is productive), so it follows that certain

presumptions in Moore would not meaningfully restrict how pore space is utilized within the

reserved mineral estate.°*

iv. Middleton v. Harlan-Wallins Coal Corp.°

Two decades after the enactment of the 1906 Act, it was still commonly understood that

the mineral estate owns the pore space within the minerals conveyed. In Middleton, the Kentucky

Supreme Court resolved a dispute in which the surface estate owners claimed that use of “apertures

and openings” in the mineral estate beneath plaintiffs land to transport coal from adjacent

landowner parcels constituted a trespass.°° The Kentucky Supreme Court observed that the

°° Id. at 499,

9 Id. at 500.

8! Jd. at 500-01,

& Yd. at 501.

83 Id.

“ See 1906 Act, § 3.

65 252 Ky. 29 (1933).

% Id. at 30.

contract at issue was silent on pore space ownership and therefore, “the rights of the parties will

be governed by the principles of law to be deduced from the mere fact of such separate ownerships,

with the incidental rights flowing therefrom to the respective owners.”°” And despite other states

such as Ohio and Pennsylvania opining on this issue years earlier, this “precise question . . . [was]

one of first impression in this jurisdiction.”°

The Middleton Court began by reviewing “cases from many of the courts of the different

states of the Union, as well as some federal and English cases, and also text authorities.” It

paraphrased these materials as “holding and announcing the correct rule to be that, as to

subterranean passages and openings made by the extraction of mineral by its owner, or lessee of

the right to mine it, the owner or lessee has the right, in the absence of contract restrictions, to use

such openings in the transportation of mineral taken from other adjoining or adjacent mining

operations without infringing upon any right of the surface owner or committing any trespass to

or on his property.” ””

According to the Kentucky Supreme Court, the various authorities reached this conclusion

by adopting one of three theories: “(a) that one who purchases or obtains the right to market the

mineral in place likewise purchases or obtains the right in the soil in which the minerals are

embodied, and becomes the owner of such encasement the same as he does of the minerals

enclosed therein;” (b) “so long as there is any of the immediate mineral in place, the owner of it,

or the one who has the right to extract it, may use the tunnels and other necessary subterranean

passages and openings, not only for the removal of the mineral taken therefrom and embedded

under the same surface rights, but also for all other lawful purposes so long as it is necessary to

maintain such openings to extract and remove the mineral under the particular surface;” or (c) “an

absolute owner of land possesses the title to the skies above its surface and to the center of the

earth below it, and may divide his title perpendicularly into longitudinal stratas and which he does

when he sells the minerals under his surface to the extent of the space occupied by the mineral

while in place, and that the purchaser whose title is so obtained takes an absolute title to the space

occupied by the minerals purchased by him.”7!

While the Kentucky Supreme Court found theory (b) to be “sound,” it took no position on

the merits of theories (a) or (c).”* Nevertheless, it concluded that transporting “foreign mineral[s]

through subterranean tunnels and passages” interferes with “no right of the owner of the surface

. in the slightest degree” and the surface estate “has no occasion to use any such subterranean

tunnels in exercising any of his reserved surface rights and privileges.”

Despite this developed body of law dealing with split estates, the Oklahoma Opinion

invokes the later “American Rule” to interpret the 1906 Act, which would hold that “in the absence

of language in the severing deed dictating a different construction ... the cavern is owned by surface

"Id.

Id.

ld.

"Id.

™ Id at 31.

owners.” In support of this result, the Oklahoma Opinion cites an order from the U.S. District

Court for the Eastern District of Oklahoma, but that order acknowledges that as late as 1978, “the

Oklahoma Supreme Court ha[d] not directly addressed ownership of pore space.”

The Oklahoma Opinion’s reliance on the American Rule is not supported by

contemporaneous authority or the interpretive rules applicable to federal Indian legislation.

Whatever the modern preference in Oklahoma or elsewhere, the relevant question must be how

the 1906 Act would have been understood in 1906, and contemporaneous authorities treated the

surface-ownership view as a minority position. In its survey of other states, the Kentucky Supreme

Court in 1933 rejected surface ownership of pore space (i.e., the American Rule) in favor of what

it then described as the “majority rule” (i.e., the English Rule). In fact, it explained that Virginia

“is the only case to be found” that presumes surface estate ownership over pore space.’ Notably,

in reviewing this referenced case, the Virginia court itself acknowledged it had adopted a minority

view:

The prevailing, if not wholly unbroken, current of authority supports the general

proposition that a grantee of coal in place is the owner, not of an incorporeal right

to mine and remove, but of a corporeal freehold estate in the coal, including the

shell or containing chamber, and that as such owner he has the absolute right, until

all of the coal has been exhausted, to use the passages opened for its removal for

any and all purposes whatsoever, including in particular the transportation of coal

from adjacent lands, so long as he operates and uses the passages with due regard

to the rights of the surface owner.”

This understanding is consistent with the general body of case law during this period. From the

late 1800s through the early 1900s, state courts relied on English legal principles in resolving pore

space disputes, which nearly always resulted in application of the English Rule.”

The Oklahoma Opinion’s interpretation of the 1906 Act under a minority rule thus seeks

to “invest old statutory terms with new meanings,” which Justice Gorsuch decried as running the

“risk [of] amending legislation outside the single, finely wrought and exhaustively considered,

procedure the Constitution commands.”” This is especially true here, where a federal court

acknowledged in 1978 that the Oklahoma Supreme Court had not yet opined on the issue of porespace ownership. Far better it is to interpret the 1906 Act in accordance with the “prevailing, if not

™ Oklahoma Op. at 5 (quoting Ellis v. Ark. La. Gas Co., 450 F. Supp. 412, 421 (E.D. Okla. 1978), aff'd, 609 F.2d 436

(10th Cir. 1979)).

7 Id. (summarizing Ellis, 450 F. Supp. at 421) (emphasis added).

fiddleton, 252 Ky. at 31 (discussing Clayborn v. Camilla Red Ash Coal Company, 128 Va. 383 (1920) asa single

outlier and noting that the Supreme Court of Alabama and Supreme Court of Arkansas have adopted the Lillibridge

and Moore doctrines).

77 Clayborn, 128 Va. at 388 (citations omitted).

78 See, e.g., Jones v. Wagner, 66 Pa. 429, 435 (1870) (relying on “English cases,” which “emanate from great ability,

and from a country in which mining, its consequences and effects are more practical, and the experience greater, than

in any other country of which we possess any knowledge” and noting that “[w]e have no case strictly of authority in

our books” or “in the books of our sister states”); Yandes v. Wright, 66 Ind. 319, 322-23 (1879) (applying English law

in holding that mineral estate is obligated to support surface estate); Youghiogheny River Coal Co. v. Allegheny Nat.

Bank, 211 Pa. 319, 323-24 (1905) (similar and applying “the law of England”).

7 New Prime Inc. v. Oliveira, 586 U.S. 105, 113 (2019) (citation and internal quotation marks omitted).

wholly unbroken” view of the early twentieth century that owners of the mineral estate rightly

control use of the caverns and voids therein.

« Case law published prior to and around 1906 makes clear that mineral

estates were understood as separate estates with expansive rights.

Beyond cases directly addressing ownership of subsurface caverns and voids, decisions

that discuss the rights and incidents of severed mineral estates provide further context for how the

Osage Nation would have reasonably understood its negotiated rights in 1906.

First, the Osage Nation would have expected that the Osage Mineral Estate carried the

ordinary incidents of mineral ownership, subject to any express limitations in the 1906 Act and a

general constraint that they may not unreasonably interfere with or injure the surface estates.*” As

the Illinois Supreme Court explained in its 1890 opinion in Consolidated Coal Co. of St. Louis v.

Schmisseur, use of the granted mineral “cannot be questioned” so long as it does not injure the

surface estate.’! And because the 1906 Act did not create a limited mineral grant but instead

conveyed the surface while broadly reserving the mineral estate, such reservation could reasonably

be understood to include the ordinary incidents of reserved subsurface formations, such as caverns

and voids.

This conclusion is further supported by the presumption that written conveyances must

expressly state that surface estates retain ownership of pore space. In 1912, the Illinois Supreme

Court in Schobert v. Pittsburg Coal & Min. Co. refused to consider the plaintiff's claim that, in

conveying subsurface coal to a mining company, “nothing passed by the grant except the coal and

the right to remove it, and that, when removed, the rooms, entries, and tunnels should revert to the

grantor.”*? The Illinois Supreme Court instead found that Lillibridge, Moore, and Consolidated

Coal were “in point” and held that because the void was entirely within the mineral estate, “the

plaintiffs, as owners of the surface, have no right or title” to it. The Illinois Supreme Court

required that any deviation from this rule be included in the conveyance instrument. Any attempt

to read the 1906 Act’s silence on this issue as impliedly conveying to surface owners the subsurface

openings within the reserved mineral stratum should be similarly rejected as inconsistent with

contemporaneous understanding of mineral estate rights and incidents.

In a case before the Ohio Supreme Court in 1906, the opinion advises that “[t]he

construction of the deed [or conveyance] is to be drawn from the circumstances of each case and

from all the words of the instrument, the object being to ascertain and give effect to the intention

of the parties.”*! There is no textual basis to infer that Congress intended to convey the pore space

within the reserved mineral estate to surface estate allottees. As discussed above, the prevailing

view treated mineral estates as corporeal interests that included the chambers and openings within

them. Courts favored this understanding because the mineral estate could use such spaces, whereas

8° Consol. Coal Co. of St. Louis v. Schmisseur, 135 Ill. 371, 376, 381 (1890)

8! Jd, at 381; see also Schobert v. Pitisburg Coal & Min. Co., 254 Ill. 474, 479 (1912) (“[P]laintiffs, as owners of the

surface, have no right or title” to the voids within a severed mineral estate—“They have no access to it; they cannot

use it; they are in no manner obstructed or injured by it.”).

82.254 III. 474, 475-77 (1912).

83 Jd. at 478-79,

84 Gill v. Fletcher, 74 Ohio St. 295, 304-05 (1906).

finding them to be part of the surface estate would simply result in frustration and interference.

Congress’s subsequent decision to transform the Osage Mineral Estate from a temporary one to

one existing in perpetuity lends further weight to this conclusion. Therefore, traditional canons of

statutory interpretation support a finding that caverns and voids within the reserved mineral

formations belong to the Osage Mineral Estate. This is true without applying the Indian canons

and is a required conclusion when they are employed.

d. Modern case law illustrates that statutory mineral reservations may carry

subsurface incidents, including storage, absent express divestiture.

Modern case law does not supply the meaning of the 1906 Act’s terms or the Osage

Nation’s reasonable expectations. Still, such cases can be instructive in confirming that mineral

conveyances have long been understood as creating a separate estate in minerals in place. And

while modern courts may no longer apply certain of the English-derived doctrines discussed above,

at least one court has interpreted a statutory reservation of minerals to include disputed subsurface

storage interests.

i Cuff v. Koslosky*

Certain Oklahoma Supreme Court decisions that post-date the 1906 Act (and therefore

cannot help in interpreting the scope of the Osage Mineral Estate) recognize that mineral

conveyances can create a separate, property-like estate in the minerals in place. That

conceptualization is consistent with the contemporaneous authorities discussed above, treating a

severed mineral estate as a corporeal interest associated with the stratum itself, including the

containing chamber and voids therein, while the mineral estate endures.

For example, in 1933, the Oklahoma Supreme Court recognized that “[t]he usual mineral

deed ... amounts to the creation of a separate estate.”*®° Such a deed is “an absolute conveyance of

[] minerals in place with title vesting in the oil and gas deferred until they are reduced to actual

possession, when property in them becomes absolute.”*’ Although Cuff does not govern the 1906

Act, it confirms that later Oklahoma precedent supports the conclusion that a mineral conveyance

may amount to “an alienation of a property right, a dismemberment of ownership, a creation of a

separate estate.”** Consistent with the majority view in 1906, the owner of such a separate

subsurface estate would not be understood as holding merely an incorporeal right to extract

substances while the surface owner retained title to the containing chamber and subsurface

openings within the conveyed mineral estate.

85 1933 OK 487, 25 P.2d 290.

86 Cuff, 1933 OK 487 at § 18; see also id. at § 27 (“a mineral grant which provides for the transfer of an interest in and

to the oil and gas and mineral rights lying in and under a certain tract of land conveying to the grantee the right to dig,

explore, and extract mineral from the granted premises without limitations as to time....”).

87 Id. at ¥ 18; see also id. at 421 (“After oil and gas have been discovered and produced from the premises under either

the oil and gas lease or the mineral deed, the corpus of the land becomes changed and depleted in proportion to the

amount of the oil and gas lifted, captured, and severed from the soil. The removal of a portion of the corpus of the

land from its unseen mineral reservoirs is not replaceable. After this removal, depletion, or production, there has been

to that extent an alienation and dismemberment of the common-law freehold estate in the land.”).

88 fd. at 927.

ii. City of Kenai v. Cook Inlet Nat. Gas Storage Alaska, LLC®

In 2016, the Alaska Supreme Court adopted an approach consistent with the English Rule.

In City of Kenai, a gas storage company asserted it had the right to use “pore space in a large

limestone formation about a mile underground” based on leases from the State of Alaska, which

held the mineral rights pursuant to Alaska Statute 38.05.125(a).”° The City of Kenai, “which owns

a significant part of the surface estate above the reservoir,” sought compensation on the theory

that, under the American Rule, it owns the pore space and therefore controls the storage rights.”!

Although the Alaska statute did not expressly mention pore space, the Alaska Supreme

Court interpreted the statutory reservation as encompassing the disputed subsurface storage

interest. Critically, City of Kenai rejected as “too simplistic” the view that pore space is merely

“the absence of something—a void constituted by surrounding structures.”* Instead, “[p]ore space

is defined by an inextricable part of the rock strata in which it is found.”%

While City of Kenai is not controlling here,” it is instructive because it treats pore space

as an incident of the formations within the reserved mineral estate, rather than a free-floating void.

This is contrary to the position in the Oklahoma Opinion that “pore space is not a substance at all,

nor can it be removed from the soil....”°° City of Kenai also illustrates that statutory reservations

of minerals do not necessarily lose every interest or incident of the reserved subsurface formation

that is not expressly referenced. This is consistent with the historical understanding discussed

above that severed mineral estates were commonly understood to be corporeal interests associated

with the subsurface stratum itself, including the containing chamber and voids within the reserved

formation, for so long as the mineral endures.

City of Kenai confirms the historical understanding of the 1906 Act. It rightly interpreted

the silence of the applicable state statute regarding pore space ownership as ambiguity and

thereafter construed it to avoid divesting by implication incidents of Alaska’s reserved mineral

estate. This underscores the importance of faithfully applying the Indian canons, including that

“congressional intent to extinguish Indian title must be plain and unambiguous and will not be

lightly implied.”°° Statutory silence is insufficient to divest the Osage Nation of valuable trust

assets absent clear language; the presumption is that valuable incidents of its reserved mineral

formations are not presumed to have been conveyed away.

8° 373 P.3d 473 (Alaska 2016).

°° Id. at 475.

"Ud.

° Id at 481.

Id.

°* This opinion takes no position on whether the term “other minerals” in the 1906 Act includes pore space. Resolving

this question is unnecessary because the historical context of the 1906 Act makes clear that the default presumption

was that mineral estates constituting incorporeal interests owned such spaces. For that reason, this Opinion does not

thoroughly address the argument in the Oklahoma Opinion that the term “other minerals” unambiguously does not

include pore space.” See Oklahoma Op. at 6.

°5 Oklahoma Op. at 4 (quoting 60 O.S.2021, § 6(B)(1)).

°° Oneida Cnty., 470 U.S. at 247-48 (cleaned up).

Also relevant, the Alaska Supreme Court held that its statutory interpretation was

“supported by the statute’s apparent purpose,” which is to “maximize revenue for the state.”°7

Likewise, Congress treated the Osage Mineral Estate as an economic trust asset—not merely an

estate within which mining may occur. In 1984, Congress clarified that the Osage Mineral Estate

includes “any right, title, or interests in any oil, gas, coal, or other mineral held by the United States

in trust for the benefit of the Osage Tribe of Indians under section 3 of the [1906] Act.”°8 Section

3 of the 1906 Act, in turn, “reserve[s] to the Osage tribe” the oil, gas, coal or other minerals covered

by the lands conveyed to individual members.”” And although the 1906 Act does not expressly

address later-developed subsurface uses, such as storage in reserved formations, the historical

context in which Congress legislated, and the requirement to resolve ambiguities in favor of the

Osage Nation, compels the conclusion that Congress did not implicitly transfer that incident to the

surface estate.

Nor is the Osage Nation limited to utilizing its mineral estate in the manner known to it in

1906. Principles of federal Indian law reject such “frozen-in-time” approaches to developing

reserved rights—absent express limitations, tribes may employ modern methods to pursue

commercial enterprises, subject principally to necessary conservation regulations.'°° The same

interpretive premise applies here. Congress broadly reserved to the Osage Nation a mineral estate

as an economic asset. It did not restrict the permissible uses of that estate to then-known practices.

Again, statutory silence should not be treated as implicitly divesting the Osage Nation from using

future technologies to extract economic benefit from its mineral estate. Instead, any ambiguity

about whether the reserved estate includes economically valuable modern uses should be resolved,

consistent with the Indian canons, to preserve the Osage Nation’s beneficial interest.

Finally, City of Kenai addressed and distinguished Ellis v. Arkansas Louisiana Gas Co—

which the Oklahoma Opinion relies on to assert “that pore space presumptively belongs to the

owner of the surface estate.”'’! Namely, the Alaska Supreme Court declined to apply Ellis’s

analysis because it concerned a private deed and thus focused on the intent of the conveying

parties, rather than on how to properly interpret a statutory reservation of minerals. That distinction

is equally relevant here.

°” City of Kenai,373 P.3d at 481.

°8 Act of Oct. 30, 1984, Pub. L. 98-605, 98 Stat. 3163, § 2(h).

° 1906 Act, § 3.

1 See, e.g., Lac Courte Oreilles Band of Lake Superior Chippewa Indians v. State of Wis., 653 F. Supp. 1420, 1430

(W.D. Wis. 1987) (“Plaintiffs are not confined to the hunting and fishing methods their ancestors relied upon at treaty

time. The method of exercise of the right is not static.”); Mille Lacs Band of Chippewa Indians v. State of Minn., 861

F. Supp. 784, 838 (D. Minn. 1994), aff'd, 124 F.3d 904 (8th Cir. 1997), aff'd sub nom. Minnesota v. Mille Lacs Band

of Chippewa Indians, 526 U.S. 172 (1999) (“The privilege granted [to the Mille Lacs Band of Chippewa Indians] in

1837 was not limited to use of any particular techniques, methods, devices, or gear... Neither the treaty journal nor

the language in the treaty indicates that the Band should be confined to techniques, methods, devices, and gear existing

in 1837.”); Puyallup Tribe v. Dep't of Game of Wash., 391 U.S. 392, 398 (1968) (“[T]he manner of fishing, the size

of the take, the restriction of commercial fishing, and the like may be regulated by the State in the interest of

conservation, provided the regulation meets appropriate standards and does not discriminate against the Indians.”).

1°! Oklahoma Op. at 5.

ili. Ellis v. Arkansas Louisiana Gas Co.'°

Even assuming Elis is instructive, it cannot define the meaning of the 1906 Act because it

post-dates the 1906 Act by over 70 years. Nevertheless, E/lis does not compel the conclusion that

the surface estate owns the subsurface voids therein. There, the severance of the mineral estate by

the surface estate owner was a commercial transaction between private parties: further, the U.S.

District Court for the Eastern District of Oklahoma cautioned that its holding was limited to the

particular circumstances of the case. !°3

Ellis identified “several factors which should be considered in arriving at a decision

concerning whether the mineral owner or the surface owner has the right and power to grant the

storage right and to receive the compensation therefor.” !! First, it looked to the intent reflected in

the severing instrument.'°° Unlike the private-party conveyance at issue in Ellis, here the

instrument is the 1906 Act, which reserved to the Osage Nation a trust-asset mineral estate.

Considering both the legal presumptions of mineral estates at the time of enactment and the Indian

canons, it would be incorrect to infer that Congress silently transferred subsurface voids within the

reserved formations to surface estate allottees. !°°

Second, Ellis distinguished between deeds conveying incorporeal rights to explore for and

produce oil, gas, and other minerals, and deeds conveying minerals in place and “the stratum of

rock containing the pore spaces within which the oil and gas may be found.”!°” Ellis relied on the

Oklahoma Supreme Court’s holding in Swnray Oil Co. v. Cortez Oil Co. to conclude that the

surface estate held the power to convey gas storage rights.'°° But Sunray Oil Co. concerned a

limited incorporeal grant that “vest[ed] no title to any oil or gas which [the grantee] does not extract

and reduce to possession, and hence no title to any corporeal right or interest.”!? A conclusion

based on Sunray Oil Co. does not map cleanly onto the 1906 Act’s reservation of a broad mineral

estate held in trust for the Osage Nation, particularly in light of the contemporaneous authorities

treating severed minerals as corporeal estates that own the voids within such minerals.

Third, Ellis considered the practical consequences of who owns the pore space, paying

particular attention to ensuring that the general welfare was promoted and energy production was

encouraged.''® The Court noted that if the “mineral interest owner and not the surface owner []

had the power to grant storage rights, it would typically mean that hundreds of severed mineral

interest owners would have to be contacted if those rights were to be obtained privately.”!'! While

the Court acknowledged “there may be instances where ... it will be necessary to secure the consent

of a large number of surface tract owners” it failed to engage with this possibility as it found “no

evidence before this court to suggest that it is the case here.”''? Even if practical consequences are

102 450 F. Supp. 412 (E.D. Okla. 1978), aff'd, 609 F.2d 436 (10th Cir. 1979).

103 Id. at 419,

104 fd. at 420.

105 fg

16 See supra, at § 1V.(a)-(b).

'°7 Ellis, 450 F. Supp. at 421.

108 fq

109 Sunray Oil Co. v. Cortez Oil Co., 1941 OK 77, § 8, 112 P.2d 792.

"0 Ellis, 450 F, Supp. at 422.

Wd

12 Iq

considered as a tertiary interpretive aid, they favor inclusion of the pore space within the Osage

Mineral Estate. Treating pore space as incidental to a single owner—the Osage Nation—would

require only a single authorization to engage in energy storage projects, whereas assigning pore

space ownership to highly fractionated surface estates may impose prohibitive barriers to initiating

subsurface storage projects. Taken together, even under £ilis’s noncontrolling framework, the

better reading is that subsurface voids within reserved mineral formations were not transferred by

implication to surface estate allottees.

e Recent Tenth Circuit authorities confirm that the Osage Mineral Estate

should be construed broadly.

The Oklahoma Opinion wrongly asserts that “Federal courts have construed ‘the other

minerals’ being held in trust for the Osage Nation in a manner that does not encompass empty

space.”''? In support of this proposition, it first cites Millsap v. Andrus, then cites United States v.

Osage Wind, LLC.'"* As explained below, both cases support—or, at a minimum, are not

inconsistent with—the positions expressed in this Opinion. As previously discussed, the

dispositive question is not whether pore space is itself a mineral; it is whether Congress, in

reserving the Osage Mineral Estate as a trust asset, conveyed an incident of the reserved subsurface

formations to surface estate owners.

i. Millsap v. Andrus |'°

In Millsap v. Andrus, the Tenth Circuit determined that “the mining of dolomite falls within

the reservation of ‘oil, coal, gas, or other minerals’” of the 1906 Act.!'° Millsap did not, however,

consider the ownership of pore space. Nonetheless, the decision’s positive outcome for the Osage

Nation resulted from an interpretation of the 1906 Act advanced throughout this Opinion.

Consistent with this Opinion, the Tenth Circuit noted that “proper construction ... depends.

on what Congress intended to reserve to the tribe.”''? Because the term “other minerals” was, at

best, unclear, it “look[ed] to the purposes of the Act for guidance in construing [its] meaning.”''*

According to Millsap, the 1906 Act reflected a balance between “bring[ing] the Osages to complete

autonomy by progressively increasing their property rights and responsibility” and “maintain[ing]

control over the more valuable resources to prevent their improvident depletion by individual tribe

members.”!'° “Nothing in the scheme or the legislative history suggests any intent to limit the

mineral reservation.” '?°

13 Oklahoma Op. at 4.

"4 Id at 4-5,

"3-717 F.2d 1326 (10th Cir, 1983).

"6 fq. at 1327.

''7 Id at 1328. However, the following sentence in Millsap appears to erroneously consider whether “[c]ontemporary

definitions of ‘minerals”” shed any light on the issue. The Court determined such definitions “are at best unclear” and

so did not consider them. Nevertheless, the position herein is that “contemporary definitions” are irrelevant—what

matters is what the terms were understood to mean at the time of drafting.

ns

"id

"20 Id. (emphasis added).

The Tenth Circuit concluded that the vague term “other minerals” in combination with the

“absence of any congressional intent to employ a specialized meaning” required that it “apply the

general rule that statutes passed for the benefit of dependent Indian tribes are to be liberally

construed with doubtful expression being resolved in favor of the Indians.”!?! Accordingly, the

meaning of “other minerals” must be read to incorporate a broad definition.'” The Millsap Court

noted this was consistent with the regulations promulgated by the U.S. Department of the Interior

that set royalties for the extraction of “all types of minerals and ore,” and “clearly includes nonhydrocarbon minerals such as limestone and dolomite.” '?3 The Tenth Circuit rejected the argument

that its holding left “virtually nothing left” to the surface owner as “of little persuasive value even

if true since it was rejected by the Supreme Court,” which held that even gravel was a mineral.'**

While the issue here is whether the statutory silence regarding ownership of voids in the

reserved subsurface formations must be resolved in favor of the Osage Nation, Millsap confirms

three salient points. First, the Osage Mineral Estate is construed broadly and in favor of the Osage

Nation, where there is ambiguity. Second, this reservation extends beyond hydrocarbons and

includes porous minerals such as limestone and dolomite—materials whose economic value often

depends in part on their physical structure and porosity. Third, Congress intended to “maintain

control over the more valuable resources”—i.e., not to convey them to surface estates. Millsap

therefore undercuts the Oklahoma Opinion’s attempt to treat the term “other minerals” as limited

to specific extractable substances and confirms that the scope of what was reserved to the Osage

Nation turns on Congress’s protective purpose, as well as the historical baseline expectations

discussed above and the Indian canons. Together, the most plausible conclusion is that the 1906

Act reserved subsurface formations to the Osage Mineral Estate.

ii. United States v. Osage Wind, LLC '°

The Oklahoma Opinion curiously argues that Osage Wind supports its conclusion that the

1906 Act conveyed pore space to surface estate allottees.'"° It incorrectly reads Osage Wind's

discussion of surface rights to mean that “the right to use or lease empty pore space falls within

the surface-estate owners’ right to virtually uninhibited use of their land.”'?” As discussed below,

Osage Wind did not address pore space ownership and cannot support an inference that the 1906

Act conveyed such ownership to surface estate owners.

In Osage Wind, the Tenth Circuit considered whether the terms “mining” and “mineral

development” in 25 C.F.R. § 211.3 (the 1906 Act’s implementing regulations) include “extraction,

sorting, crushing, and use of minerals as part of excavation work.”!?8 “Because there is ambiguity

in the scope of ‘mineral development” the court twice interpreted the term in favor of the Osage

121 Id at 1328-29.

122 Id at 1329.

"3 Id; see also 25 C.F.R. § 211.3 (“Minerals includes both metalliferous and non-metalliferous minerals; all

hydrocarbons, including oil and gas, coal and lignite of all ranks; geothermal resources; and includes but is not limited

to, sand, gravel, pumice, cinders, granite, building stone, limestone, clay, silt, or any other energy or non-energy

mineral.”).

'24 Td at 1329 n.6 (discussing Watt v. Western Nuclear, 462 U.S. 36, 103 (1983)).

125.871 F.3d 1078 (10th Cir. 2017).

'26 Oklahoma Op. at 4-5.

"7 Id at.

18 87] F.3d at 1081.

Nation: first, it concluded that “mineral development” includes “acting upon the minerals to

exploit the minerals themselves”; and second, that the phrase “includes the sorting and crushing

of minerals for the purpose of backfilling and stabilization.” '??

The Tenth Circuit rejected Osage Wind’s argument that these broad constructions in favor

of the Osage Nation “contradicts the [1906] Act itself.”!°° While the 1906 Act grants “expansive

authority” to surface estates, this was “necessarily limited by [its] reservation of the mineral estate

to the Osage Nation.” 3! Thus, “surface construction activities may often implicate and disrupt the

mineral estate—building a basement or swimming pool necessarily involves digging a hole in the

ground, displacing rock and soil in the process.”'** However, Osage Wind clarified that merely

“encountering or disrupting the mineral estate does not trigger the definition of ‘mining’ under 25

C.F.R. § 211.3." This holding is consistent with the structure of 25 C.F.R. § 211.3, which

exempts from the definition of mining “any use of common-variety minerals that is less than 5,000

cubic yards.”'*! This structure makes intuitive sense, as the purpose of the regulations is not to

require a mining lease for each and every instance in which a surface owner may dig into the

surface. Thus, Osage Wind held that certain conduct on the surface may not constitute “mining

activity” even if it disrupts or encounters the mineral estate.

The Oklahoma Opinion misreads these portions of Osage Wind as supporting the

conclusion that “using pore space does not necessarily entail the extraction and development of oil

and gas or other minerals,” and therefore, “the right to use or lease empty pore space falls within

the surface-estate owners’ right.”!°> This is incorrect for the reasons explained above and

summarized as follows: first, Osage Wind merely held that not all removal of minerals from the

surface constitutes “mining” under 25 C.F.R. § 211.3; second, the Tenth Circuit expressly

recognized that such conduct may nevertheless “implicate and disrupt” the Osage Mineral Estate;

and third, Osage Wind did not address pore space ownership. As demonstrated by the admonitions

in Osage Wind itself, activity implicating minerals within the Osage Reservation requires a factspecific statutory analysis that often involves the invocation of the Indian canons in favor of the

Osage Nation.

f. The 1906 Act cannot be interpreted to abrogate the Osage Nation’s reserved

rights.

As explained in this Opinion, the text of the 1906 Act itself, as well as the legal

presumptions at the time of its enactment, compel the conclusion that ownership of pore space

within the reserved mineral formations was not conveyed to surface estate allottees. This

conclusion is reinforced by the rule that Congress must speak clearly to divest a tribe of treatyrecognized property rights. Nothing in the 1906 Act reflects an intent to transfer rights that would

'29 Id, at 1092; see also id, at 1091 (noting that Osage Wind construction of “mineral development” was “reasonable”

but because the term was “ambiguous in this regulation, the Indian canon of interpretation tilts our hand toward a

construction more favorable to Osage Nation, so we adopt the broader definition,” which “includes acting upon the

minerals to exploit the minerals themselves.”).

130 fd. at 1092.

Sd.

132 Id.

133 fd

14 Id

85 Oklahoma Op. at 5.

have been understood as incidental to the mineral formations identified as part of the Osage

Reservation pursuant to a negotiated treaty and agreement with the United States.

Under the 1865 Treaty, the Osage sold or otherwise transferred certain reservation lands in

Kansas to the United States, with lands not conveyed referred to thereafier as the Osage

“diminished reservation.” °° Among other things, the 1865 Treaty further contemplated that the

Osage would relocate to a different reservation in modern-day Oklahoma:

It is also agreed by said contracting parties, that if said Indians should agree to

remove from the State of Kansas, and settle on lands to be provided for them by the

United States in the Indian Territory on such terms as may be agreed on between

the United States and the Indian tribes now residing in said Territory or any of them,

then the diminished reservation shall be disposed of by the United States ... [and]

proceeds of the sale of said diminished reserve may be used by the United States in

the purchase of lands for a suitable home for said Indians in said Indian Territory. '°7

Less than five years later, Congress passed legislation which provided the terms and conditions

governing this relocation. '3* Relevant here, when the Osage assented to such terms and conditions

in the Drum Creek Treaty of 1870, it explicitly understood that it was transferring to the United

States its reservation in Kansas for “a permanent home in the Indian Territory.” '*?

In 1872, Congress established the Osage Reservation in the Indian Territory, consistent

with the 1865 Treaty, the 1870 Relocation Act, and the Drum Creek Treaty of 1870.'"° This

reservation became part of the Oklahoma Territory in 1890,'*! and was not subject to any relevant

legislation until the 1906 Act, which severed the surface estate from Osage Mineral Estate for

transfer to individual Osage allottees. '”

This history makes clear that interpreting the 1906 Act requires attention to the Osage

Nation’s treaty-protected land rights. It is beyond doubt that the Osage Reservation included pore

space when it was established by Congress in 1872. The Oklahoma Opinion does not assert

otherwise. Therefore, abrogation of the Osage Nation’s rights to own and develop this trust asset

can be realized only if “Congress’ intention is ... clear and plain.”!"3

The 1906 Act contains no “explicit statutory language”! that would divest the Osage

Nation of its pore space. As such, abrogation can be found only if the applicable statute’s text,

structure, and history make “clear and plain” Congress’s intent. The Oklahoma Opinion fails to

undertake this analysis, and this Opinion finds no basis for concluding that Congress intended the

1906 Act to abrogate the Osage Nation’s treaty-recognized rights to its reserved pore space,

'8¢ 1865 Treaty, arts. 1-2, 12.

87 Id. atart. 16.

88 1870 Relocation Act.

139 Id. at 362.

'° Act of June 5, 1872, ch. 310 17 Stat. 228.

41 Act of May 2, 1890, ch. 182, 26 Stat. 81.

'? Letter from Tara Sweeney, Assistant Secretary - Indian Affairs, to Geoffrey Standing Bear, Principal Chief, Osage

Nation at 1-2 (June 26, 2020).

'8 United States v. Dion, 476 U.S. 734, 738 (1986) (citing F. Cohen, Handbook of Federal Indian Law 223 (1982)).

' Washington v. Washington Commercial Passenger Fishing Vessel Assn., 443 U.S. 658, 690 (1979).

especially as there was a contemporaneous presumption that mineral estates were understood as

corporeal estates, including the rights to use those caverns, voids, and spaces within the mineral

formations.

VI. Question 2: Oklahoma law does not control the interpretation of the 1906 Act.

The analysis in the Oklahoma Opinion is largely guided by its starting point that the “‘rights

attached to the ownership of property conveyed by the [Federal] government will be determined

by the states’ so long as state law does not ‘impair the efficacy of the grants or the use and

enjoyment of the property by the grantee.’”!#> Because current Oklahoma law “unquestionably

supports the allottees’ rights,” and the 1906 Act “does not disclaim the application of state law,”

the Oklahoma Opinion concludes that “Oklahoma law defines the rights attached to the individual

allottees’ ownership of the surface,” which includes “the right to use and lease pore space.” '"° This

Opinion finds the Oklahoma Opinion’s framing to be doctrinally unsound.

The Oklahoma Opinion’s first authority, Choctaw & Chickasaw Nations v. Board of

County Commissioners of Love County, Oklahoma,'*’ is inapplicable here. It is correct that the

Tenth Circuit held that the “disposition of Indian lands under the guardianship of the United States

is a matter of intention of the grantor and if its intention be not otherwise shown, it will be taken

to have assented that its conveyance should be construed and given effect in this particular

according to the law of the State in which the land lies.”'*8 But in Choctaw & Chickasaw Nations,

land was conveyed without reserving or severing the surface estate from the subsurface mineral

estate. As such, the Tenth Circuit did not consider state law as relevant in defining the outer limits

of a reserved trust asset.'“? Moreover, the applicable federal statute in Choctaw & Chickasaw

Nations was passed afier Oklahoma achieved statehood in 1907. The 1906 Act, on the other hand,

predates statehood, reserves an asset in trust for the Osage Nation beneath the surface estates, and

specifies those instances where Oklahoma law applies (i.c., probate matters).'*° Therefore, the

portion of the rule stated in Choctaw & Chickasaw regarding the application of state law is here

misplaced.

The Oklahoma Opinion’s second authority, Oneida Indian Nation of N.Y. v. Oneida

Cnty.,!°' does not compel a different result. There, the Supreme Court stated that “whatever

incidents or rights attach to the ownership of property conveyed by the government will be

determined by the states, subject to the condition that their rules do not impair the efficacy of the

grants or the use and enjoyment of the property by the grantee.” '** However, the Court in the very

next sentence explained that questions involving the “possessory rights to tribal lands” are “wholly

apart from the application of state law principles which normally and separately protect a valid

' Oklahoma Op. at 4, 5 (quoting Oneida, 414 U.S. at 677).

M6 I

'97 361 F.2d 932 (10th Cir. 1966)

M8 Jd. at 933 (cleaned up).

9 [dat 934.

'3° 1906 Act, § 6 (“That the lands, moneys, and mineral interests, herein provided for, of any deceased member of the

Osage tribe shall descend to his or her legal heirs, according to the laws of the Territory of Oklahoma, or of the State

in which said reservation may be hereinafler incorporated...” (emphasis added)).

151 414 U.S. 661 (1974).

'S2 Id. at 677 (quotation marks and citation omitted).

sion.”! Rather, questions involving tribal property and the extinguishment of

154

right of posse:

Indian title arise under federal law, not state law.

Justice Rehnquist’s concurrence further confirms this:

Commonly, the grant of a land patent to a private party carries with it no guarantee

of continuing federal interest.... On the contrary, as the majority points out, the

land thus conveyed was generally subject to state law thereafter..... The majority

today finds this strict rule inapplicable to this case, and for good reason. In contrast

to the typical instance in which the Federal Government conveys land to a private

entity, the Government, by transferring land rights to Indian tribes, has not placed

the land beyond federal supervision. Rather the Federal Government has shown a

continuing solicitude for the rights of the Indians in their land. The Nonintercourse

Act of 1790 manifests this concern in statutory form. Thus, the Indians’ right to

possession in this case is based not solely on the original grant of rights in the land

but also upon the Federal Government’s subsequent guarantee. Their claim is

clearly distinguishable from the claims of land grantees for whom the Federal

Government has taken no such responsibility.'°°

Under Oneida Indian Nation of N.Y., federal law thus controls the analysis here, not Oklahoma

state law, including its law addressing pore space ownership enacted over 100 years after the 1906

Act, '56

The judicial precedents regarding pore space at and around 1906 provide a historical

baseline for what the Osage Nation would have understood to be reserved to it in the 1906 Act. As

133 yg.

'S4 Id, at 678.

'5 Id, at 683-84 (Rehnquist, J. concurring).

'S¢ See 60 Okla. Stat. § 60-6 (2011). The Oklahoma Opinion’s remaining authorities are inapposite. United States v,

Oklahoma Gas & Elec. Co. considered whether maintenance of electrical service lines within a highway running over

Indian allotments constituted highway use. 318 U.S. 206, 207 (1943). The Court concluded that “the explicit reference

... to state law ... indicate that the question in this case is to be answered by reference to that law.” /d. at 210. The

1906 Act contains no such reference. See also, Millsap v. Andrus, 717 F.2d at 1328 (determining whether “other

minerals” in the 1906 Act included dolomite without reference to state law). The Oklahoma Opinion then quotes

Montana y. United States out of context. See Oklahoma Op. at 6-7. While it is correct that the Court held that “title

to the land is governed by state law,” the preceding sentences make clear that this discussion was limited to lands

underlying navigable waters. 450 U.S. $44, 551 (1981) (“{T]he ownership of land under navigable waters is an

incident of sovereignty. As a general principle, the Federal Government holds such lands in trust for future States, to

be granted to such States when they enter the Union and assume sovereignty on an ‘equal footing’ with the established

States. After a state enters the Union, title to the land is governed by state law.” (citations omitted)). The Oklahoma

Opinion’s reliance on Oklahoma v. Castro-Huerta, fares no better, as that case concerned state_criminal jurisdiction

in Indian country. 597 U.S. 629, 638 (2022) (“The central question that we must decide, therefore, is whether the

State’s authority to prosecute crimes committed by non-Indians against Indians in Indian country has been

preempted.”). The Oklahoma Opinion similarly misapplies Plains Commerce Bank v. Long Fam. Land & Cattle Co

Oklahoma Op. at 7 (discussing Plains Com. Bank, 554 U.S. 316, 331 (2008) (considering whether tribe may regulate

the sale of non-Indian fee land). A tribe’s authority to regulate the sale of non-Indian fee land has no bearing on

whether the Osage Mineral Estate includes pore space. Therefore, the Oklahoma Opinion’s position that these

authorities support the application of state law here is incorrect.

discussed above, the 1906 Act predates Oklahoma statehood, but notably, even its earliest, post-

1906 Act property laws do not support a contrary result.

In 1910, Oklahoma defined real or immovable property to consist of “land, that which is

affixed to land, that which is incidental or appurtenant to land, and that which is immoveable by

law.” '57 It then defined land as “the solid material of the earth, whatever may be the ingredients of

which it is composed, whether soil, rock or other substance.” !°’ Only in 201 1—the same year the

first CO2 storage well was permitted—did Oklahoma amend its statutory definition of land to

include pore space: “Land is the solid material of the earth, whatever may be ingredients of which

it is composed, whether soil, rock or other substance, and includes any pore space.” '*? In that same

amendment, Oklahoma added new language to further clarify that—

pore space is real property and, until title to the pore space or rights, interests or

estates in the pore space are separately transferred, pore space is property of the

person or persons holding title to the land surface above it.

This Opinion declines to interpret the 1910 statute as including pore space by implication, as that

would render the later inclusion of pore space surplusage.'°° Such an inference is similarly rejected

by the federal district court in Ellis, which described pore space ownership in Oklahoma as

unsettled as late as 1978,'¢!

The Supreme Court in 1979 provided additional clarity in Wilson v. Omaha Indian Tribe,

where it evaluated the appropriateness of relying on state law to decide a property dispute between

the tribe and non-Indians: “[W ]here the Government has never parted with title and its interest in

the property continues,” tribal property rights “depend[] on federal law, ‘wholly apart from the

application of state law principles which normally and separately protect a valid right of

possession.””'©? While Wilson ultimately found that state law principles should be borrowed in

that case, it did so after asking whether there was (1) a “need for a nationally uniform body of law

to apply in situations comparable to this,” (2) “whether application of state law would frustrate

federal policy or functions,” and (3) “the impact a federal rule might have on existing relationships

under state law.”!03

Here, the application of state law would create both legal and practical concerns. First, a

uniform body of law is necessary for the United States to manage subsurface trust assets across

reservations located in states with varying pore space laws. Second, application of Oklahoma law

in this instance would frustrate the BIA’s attempt to regulate development within the Osage

Mineral Estate and lead to disputes between the Osage Nation and surface estate owners regarding

primacy and interference by one estate in the rights of the other. Third, refusal to apply Oklahoma

law in this instance would have little to no impact on existing relationships under state law, as

'STR.L.1910, § 6588 (cleaned up).

'58 /d., § 6590 (amended language emphasized).

'S° 60 Okla. Stat. § 60-6(A) (2011).

'©9 See Williams v. Taylor, 529 U.S. 362, 404 (2000) (“It is, however, a cardinal principle of statutory construction

that we must ‘give effect, if possible, to every clause and word of a statute.’”) (O’Connor, J. concurring) (quoting

United States v. Menasche, 348 U.S. 528, 538-539 (1955)).

'61 450 F. Supp. at 421.

'©? 442 U.S. 653, 670 (1979) (quoting Oneida Indian Nation, 414 U.S., at 677).

13 Id. at 672-73.

Oklahoma enacted its pore space law in 2011 and has yet to permit pore space activity within the

P P: y' Pp pi Pp y

Osage Reservation. '

VIE. Conclusion

Based on the foregoing analysis, this Opinion concludes that the 1906 Act did not convey

pore space within reserved mineral formations to surface estate allottees. The statute contains no

explicit language authorizing such conveyance, and without a clear and plain statement divesting

the Osage Nation of this treaty-recognized trust asset, title to pore space was unaffected by the

1906 Act and remained with the United States in trust for the Osage Nation.

Assuming one finds the 1906 Act’s silence regarding pore space ownership to create

ambiguity, a review of contemporaneous property law principles in and around 1906 provides a

historical baseline. Under the prevailing view, severed mineral estates were understood as

corporeal estates to minerals in place, carrying with them the right to use and control the openings,

chambers, and voids within the severed mineral formations, subject to limited and irrelevant

constraints. Later authorities reinforce the same conceptual framework, with at least one court

interpreting a statutory mineral reservation as reserving subsurface storage rights to the mineral

estate, even where the statute did not expressly reference pore space. With this understanding, this

Opinion again concludes that the 1906 Act did not divest the Osage Nation of ownership in its

pore space. This determination is reached without applying the Indian canons. Applying such

canons—a requirement where there is ambiguity in federal legislation impacting Indian tribes

compels the result.

This conclusion also makes practical sense. The Osage Mineral Estate includes porous

minerals such as limestone and dolomite, and treating the voids and porosity within those reserved

formations as belonging to the surface would fracture control of a single subsurface formation in

a manner that would predictably force either the mineral estate or the surface estate to interfere

with the other’s rights to develop the resource. Absent clear statutory language requiring that

outcome, this Opinion will not read implied divestiture into the 1906 Act. !®

For these reasons, this Opinion finds that pore space within the reserved mineral formations

of the Osage Reservation remains a trust asset of the Osage Nation.

't The Osage Nation enacted its own pore space law in 2024, See 22 ONC § 2-104 (2024). In contrast to Oklahoma’s

pore space law—seemingly enacted only after new commercial opportunities presented themselves—Osage Nation

law confirmed decades of past practice in which the Osage Minerals Council authorized CO2 injection of pore space

for enhanced oil and gas recovery. While this extraction technique is but one of many ways in which Osage Nation

pore space can be utilized, it further demonstrates that both Oklahoma and the Osage Nation have long understood

that pore space within reserved mineral formations belong to the Osage Mineral Estate.

'e> Oklahoma law is in accord. For example, in 2024, the U.S. District Court for the Northern District of Oklahoma

held that the Osage Mineral Estate may assert a claim for trespass where one “occup[ies] [] the mineral estate” without

consent. United States v. Osage Wind, LLC, 2024 WL 5158188, at *16 (N.D. Okla. Dec. 18, 2024); see also Edwards

v, Lachman, 1974 OK 58, § 1, 534 P.2d 670, 672 (“The drilling of [a] well into the adjacent property constituted a

sub-surface trespass.”); Dulaney v. Oklahoma State Dep't of Health, 1993 OK 113, 4 10, 868 P.2d 676, 681 (Permit

for landfill that would pollute groundwater “granted by the Department of Health allows the use of the surface estate

in a manner which may impair recognized and well-defined property rights of the mineral interest owner.”).

The Oklahoma Opinion’s attempt to compel a different result by importing after-the-fact

Oklahoma state law is legally unfounded. The 1906 Act contains no reference to state law on this

topic; the Osage Mineral Estate is a trust asset held for the benefit of the Osage Nation; and

Oklahoma did not enact its pore-space statute until 105 years after the passage of the 1906 Act.

Applying that later-enacted state law here would conflict with longstanding Supreme Court

precedent limiting the application of state law to Indian trust assets and would disrupt more than a

century of the Osage Nation’s settled expectations.

This Opinion therefore finds that Oklahoma law cannot control the interpretation of the

1906 Act, including ownership of pore space within the reserved mineral formations of the Osage

Reservation.

Respectfully submitted,

6220" —=

Clinton N. Patterson, Attorney General