The Crow Tribe first inhabited modern-day Montana more than three centuries ago. Montana v. United States, 450 U. S. 544, 547 (1981). The Tribe was nomadic, and its members hunted game for subsistence. J. Medicine Crow, From the Heart of the Crow Country 4–5, 8 (1992). The Bighorn Mountains of southern Montana and northern Wyoming “historically made up both the geographic and the spiritual heart” of the Tribe’s territory. Brief for Crow Tribe of Indians as Amicus Curiae 5.

The westward migration of non-Indians began a new chapter in the Tribe’s history. In 1825, the Tribe signed a treaty of friendship with the United States. Treaty With the Crow Tribe, Aug. 4, 1825, 7 Stat. 266. In 1851, the Federal Government and tribal representatives entered into the Treaty of Fort Laramie, in which the Crow Tribe and other area tribes demarcated their respective lands. Montana, 450 U. S., at 547–548. The Treaty of Fort Laramie specified that “the tribes did not ‘surrender the privilege of hunting, fishing, or passing over’ any of the lands in dispute” by entering the treaty. Id., at 548.

After prospectors struck gold in Idaho and western Montana, a new wave of settlement prompted Congress to initiate further negotiations. See F. Hoxie, Parading Through History 88–90 (1995). Federal negotiators, including Commissioner of Indian Affairs Nathaniel G. Taylor, met with Crow Tribe leaders for this purpose in 1867. Taylor acknowledged that “settlements ha[d] been made” upon the Crow Tribe’s lands and that their “game [was] being driven away.” Institute for the Development of Indian Law, Proceedings of the Great Peace Commission of 1867–1868, p. 86 (1975) (hereinafter Proceedings). He told the assembled tribal leaders that the United States wished to “set apart a tract of [Crow Tribe] country as a home” for the Tribe “forever” and to buy the rest of the Tribe’s land. Ibid. Taylor emphasized that the Tribe would have “the right to hunt upon” the land it ceded to the Federal Government “as long as the game lasts.” Ibid.

At the convening, Tribe leaders stressed the vital importance of preserving their hunting traditions. See id., at 88 (Black Foot: “You speak of putting us on a reservation and teaching us to farm.... That talk does not please us. We want horses to run after the game, and guns and ammunition to kill it. I would like to live just as I have been raised”); id., at 89 (Wolf Bow: “You want me to go on a reservation and farm. I do not want to do that. I was not raised so”). Although Taylor responded that “[t]he game w[ould] soon entirely disappear,” he also reassured tribal leaders that they would “still be free to hunt” as they did at the time even after the reservation was created. Id., at 90.

The following spring, the Crow Tribe and the United States entered into the treaty at issue in this case: the 1868 Treaty. 15 Stat. 649. Pursuant to the 1868 Treaty, the Crow Tribe ceded over 30 million acres of territory to the United States. See Montana, 450 U. S., at 547–548; Art. II, 15 Stat. 650. The Tribe promised to make its “permanent home” a reservation of about 8 million acres in what is now Montana and to make “no permanent settlement elsewhere.” Art. IV, 15 Stat. 650. In exchange, the United States made certain promises to the Tribe, such as agreeing to construct buildings on the reservation, to provide the Tribe members with seeds and implements for farming, and to furnish the Tribe with clothing and other goods. 1868 Treaty, Arts. III–XII, id., at 650–652. Article IV of the 1868 Treaty memorialized Commissioner Taylor’s pledge to preserve the Tribe’s right to hunt off-reservation, stating:

*4 “The Indians ... shall have the right to hunt on the unoccupied lands of the United States so long as game may be found thereon, and as long as peace subsists among the whites and Indians on the borders of the hunting districts.” Id., at 650.

A few months after the 1868 Treaty signing, Congress established the Wyoming Territory. Congress provided that the establishment of this new Territory would not “impair the rights of person or property now pertaining to the Indians in said Territory, so long as such rights shall remain unextinguished by treaty.” An Act to Provide a Temporary Government for the Territory of Wyoming (Wyoming Territory Act), July 25, 1868, ch. 235, 15 Stat. 178. Around two decades later, the people of the new Territory adopted a constitution and requested admission to the United States. In 1890, Congress formally admitted Wyoming “into the Union on an equal footing with the original States in all respects,” in an Act that did not mention Indian treaty rights. An Act to Provide for the Admission of the State of Wyoming into the Union (Wyoming Statehood Act), July 10, 1890, ch. 664, 26 Stat. 222. Finally, in 1897, President Grover Cleveland set apart an area in Wyoming as a public land reservation and declared the land “reserved from entry or settlement.” Presidential Proclamation No. 30, 29 Stat. 909. This area, made up of lands ceded by the Crow Tribe in 1868, became known as the Bighorn National Forest. See App. 234; Crow Tribe of Indians v. Repsis, 73 F. 3d 982, 985 (CA10 1995).


Petitioner Clayvin Herrera is a member of the Crow Tribe who resides on the Crow Reservation in Montana. In 2014, Herrera and other Tribe members pursued a group of elk past the boundary of the reservation and into the neighboring Bighorn National Forest in Wyoming. They shot several bull elk and returned to Montana with the meat. The State of Wyoming charged Herrera for taking elk off-season or without a state hunting license and with being an accessory to the same.

In state trial court, Herrera asserted that he had a protected right to hunt where and when he did pursuant to the 1868 Treaty. The court disagreed and denied Herrera’s pretrial motion to dismiss. See Nos. CT–2015–2687, CT–2015–2688 (4th Jud. Dist. C. C., Sheridan Cty., Wyo., Oct. 16, 2015), App. to Pet. for Cert. 37, 41. Herrera unsuccessfully sought a stay of the trial court’s order from the Wyoming Supreme Court and this Court. He then went to trial, where he was not permitted to advance a treaty-based defense, and a jury convicted him on both counts. The trial court imposed a suspended jail sentence, as well as a fine and a 3-year suspension of Herrera’s hunting privileges.

Herrera appealed. The central question facing the state appellate court was whether the Crow Tribe’s off-reservation hunting right was still valid. The U. S. Court of Appeals for the Tenth Circuit, reviewing the same treaty right in 1995 in Crow Tribe of Indians v. Repsis, had ruled that the right had expired when Wyoming became a State. 73 F. 3d, at 992–993. The Tenth Circuit’s decision in Repsis relied heavily on a 19th-century decision of this Court, Ward v. Race Horse, 163 U. S. 504, 516 (1896). Herrera argued in the state court that this Court’s subsequent decision in Minnesota v. Mille Lacs Band of Chippewa Indians, 526 U. S. 172 (1999), repudiated Race Horse, and he urged the Wyoming court to follow Mille Lacs instead of the Repsis and Race Horse decisions that preceded it.

*5 The state appellate court saw things differently. Reasoning that Mille Lacs had not overruled Race Horse, the court held that the Crow Tribe’s 1868 Treaty right expired upon Wyoming’s statehood. No. 2016–242 (4th Jud. Dist., Sheridan Cty., Wyo., Apr. 25, 2017), App. to Pet. for Cert. 31–34. Alternatively, the court concluded that the Repsis Court’s judgment merited issue-preclusive effect against Herrera because he is a member of the Crow Tribe, and the Tribe had litigated the Repsis suit on behalf of itself and its members. App. to Pet. for Cert. 15–17, 31; App. 258. Herrera, in other words, was not allowed to relitigate the validity of the treaty right in his own case.

The court also held that, even if the 1868 Treaty right survived Wyoming’s entry into the Union, it did not permit Herrera to hunt in Bighorn National Forest. Again following Repsis, the court concluded that the treaty right applies only on “unoccupied” lands and that the national forest became categorically “occupied” when it was created. See App. to Pet. for Cert. 33–34; Repsis, 73 F. 3d, at 994. The state appellate court affirmed the trial court’s judgment and sentence.

The Wyoming Supreme Court denied a petition for review, and this Court granted certiorari. 585 U. S. ___ (2018). For the reasons that follow, we now vacate and remand.