In McGirt v. Oklahoma, a member of the Seminole Nation was prosecuted in Oklahoma state court of serious sexual offenses and sentenced to 1,000 years plus life in prison. He argued that the state court lacked jurisdiction because under the Major Crimes Act, only federal courts had jurisdiction over crimes committed by an Indian on “Indian country,” and he argued that his crimes occurred on the Creek Reservation.
The Oklahoma Court of Criminal Appeals rejected that argument, but the Court, in a 5-4 decision by Justice Gorsuch, reversed, holding that land reserved for the Creek Nation back in the 19th Century, after the Trail of Tears, remained a reservation today because Congress had not passed legislation expressly limiting that grant. The many promises broken in the interim did not diminish the grant, and accordingly the majority held “the government to its word.” Chief Justice Roberts, joined by Justices Alito and Kavanaugh, and Thomas in part, dissented, arguing that Congress implicitly intended to disestablish the reservation by its actions over the years, and warned that the creation of a new reservation over much of Oklahoma threatened to destabilize and undermine the State’s ability to enforce the law. Justice Thomas filed a separate dissent arguing that the Court should not reverse the State court’s decision because the defendant’s argument was procedurally barred under State law.
A link to the opinion is here: https://www.supremecourt.gov/opinions/19pdf/18-9526_9okb.pdf