The US Supreme Court has ruled that a huge chunk of the state of Oklahoma - almost half of the eastern part of the state - belongs to Native Americans, the BBC reports.
Oklahoma's second-largest city, Tulsa, is included in the area that the judges ruled should be considered a reservation.
The ruling means that only federal prosecutors have jurisdiction over the reservation's residents, and tribal members may also be exempt of state taxes.
The ruling was 5-4, with Chief Justice Roberts among those dissenting, noting in his arguments that the ruling would create havoc in the judicial system, as Native Americans prosecuted and convicted by state courts in previous decades could now potentially appeal and have their convictions overturned.
Justice Neil Gorsuch wrote the court's majority opinion, referring to the "Trail of Tears," the forcible relocation of Native Americans in the nineteenth century to Oklahoma, after which the government promised that the land to which the tribes were being relocated would forever belong to them.
"Today we are asked whether the land these treaties promised remains an Indian reservation for purposes of federal criminal law," Gorsuch wrote. "Because Congress has not said otherwise, we hold the government to its word."
Around 1.8 million people - of whom about 15% are Native American - live on the land, which spans three million acres.