The Supreme Court on Thursday ruled that a large portion of Oklahoma is Native American reservation land, belonging to the Creek Nation, and is therefore not subject to state jurisdiction. In a 5-4 decision, the Supreme Court ruled that because Congress failed to formally undo the Creek Nation’s 19th-century reservation, the land located in eastern Oklahoma remains “Indian Country” for purposes of federal criminal law.

“Today we are asked whether the land these treaties promised remains an Indian reservation for purposes of federal criminal law. Because Congress has not said otherwise, we hold the government to its word,” conservative Justice Neil Gorsuch, who authored the opinion, wrote. The case was brought by Jimmy McGirt, a member of the Creek Nation, who was convicted by an Oklahoma court of raping a 4-year-old in 1997. McGirt argued that Oklahoma did not have jurisdiction to review his case because the alleged crime took place within the boundaries of the Creek Nation’s reservation.