WASHINGTON >> The Supreme Court ruled today that a large chunk of eastern Oklahoma remains an American Indian reservation, a decision that state and federal officials have warned could throw Oklahoma into chaos.

The court’s 5-4 decision, written by Justice Neil Gorsuch, means that Oklahoma prosecutors lack the authority to pursue criminal cases against American Indian defendants in parts of Oklahoma that include most of Tulsa, the state’s second-largest city.

“On the far end of the Trail of Tears was a promise. Forced to leave their ancestral lands in Georgia and Alabama, the Creek Nation received assurances that their new lands in the West would be secure forever. … 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,” Gorsuch wrote in a decision joined by the court’s liberal members.

The court’s ruling casts doubt on hundreds of convictions won by local prosecutors. But Gorsuch suggested optimism.

“In reaching our conclusion about what the law demands of us today, we do not pretend to foretell the future and we proceed well aware of the potential for cost and conflict around jurisdictional boundaries, especially ones that have gone unappreciated for so long. But it is unclear why pessimism should rule the day. With the passage of time, Oklahoma and its Tribes have proven they can work successfully together as partners,” he wrote.

Oklahoma’s three U.S. attorneys quickly released a joint statement expressing confidence that “tribal, state, local and federal law enforcement will work together to continue providing exceptional public safety” under the ruling.

Jonodev Chaudhuri, ambassador of the Muscogee (Creek) Nation and a former chief justice of the tribe’s Supreme Court, said the state’s argument that such a ruling would cause legal havoc in the state was overblown.

“All the sky-is-falling narratives were dubious at best,” Chaudhuri said. “This would only apply to a small subset of Native Americans committing crimes within the boundaries.

“This case didn’t change ownership of any land. It didn’t impact the prosecutions of non-Indians in any way. All it did was bring clarity to jurisdictional questions regarding the border, and it enhanced the Creek Nation’s ability as a sovereign nation to work with other sovereign interests to protect people and to work in common interests.”

Forrest Tahdooahnippah, a Comanche Nation citizen and attorney who specializes in tribal law, said the ruling’s short-term implications are largely confined to the criminal context and that serious felonies committed by Native Americans in parts of eastern Oklahoma will be subject to federal jurisdiction.

“In the long term, outside of the criminal context, there may be some minor changes in civil law,” he said. “The majority opinion points out assistance with Homeland Security, historical preservation, schools, highways, clinics, housing, and nutrition programs, as possible changes. The Creek Nation will also have greater jurisdiction over child welfare cases involving tribal members.”

The case, which was argued by telephone in May because of the coronavirus pandemic, revolved around an appeal by an American Indian who claimed that state courts had no authority to try him for a crime committed on reservation land that belongs to the Muscogee (Creek) Nation.

The reservation once encompassed 3 million acres (12,100 square kilometers), including most of Tulsa.

The Supreme Court, with eight justices taking part, failed to reach a decision last term when it reviewed a federal appeals court ruling in a separate case that threw out a state murder conviction and death sentence. In that case, the appeals court said the crime occurred on land assigned to the tribe before Oklahoma became a state and Congress never clearly eliminated the Creek Nation reservation it created in 1866.

The case the justices decided today involved 71-year-old Jimcy McGirt, who is serving a 500-year prison sentence for molesting a child. Oklahoma state courts rejected his argument that his case does not belong in Oklahoma state courts and that federal prosecutors should instead handle his case.

McGirt could potentially be retried in federal court, as could Patrick Murphy, who was convicted of killing a fellow tribe member in 1999 and sentenced to death. But Murphy would not face the death penalty in federal court for a crime in which prosecutors said he mutilated the victim and left him to bleed to death on the side of a country road about 80 miles (130 kilometers) southeast of Tulsa.

Following the ruling, the state of Oklahoma issued a joint statement with the Muscogee (Creek), Cherokee, Chickasaw, Choctaw and Seminole nations in which they vowed to work together on an agreement to address any unresolved jurisdictional issues raised by the decision.

“The Nations and the State are committed to ensuring that Jimcy McGirt, Patrick Murphy, and all other offenders face justice for the crimes for which they are accused,” the statement read. “We have a shared commitment to maintaining public safety and long-term economic prosperity for the Nations and Oklahoma.”