Fifteen years ago, an assistant federal public defender and a defense investigator found a cross commemorating a murder beside a deserted road in eastern Oklahoma. It wasn’t where it was supposed to be. Law-enforcement records said it should have been about a mile and a quarter away. That slight discrepancy has led to a Supreme Court case slated for oral arguments on November 27. Formally at stake is the fate of a brutal murderer, Patrick Dwayne Murphy. But the Court must also decide whether that roadside crime scene is now and has always been a part of the Muscogee Creek Reservation.

Not just that scene—as much as 5,000 other square miles, including much of the city of Tulsa.

If the answer is “Yes,” there is a chance that the same will be true of historic reservations originally granted to the other “civilized tribes” that were removed to what is now Oklahoma by Andrew Jackson—the Cherokee, Chickasaw, Choctaw, and Seminole nations—meaning that roughly half of Oklahoma might be reservation land.

The homemade monument the lawyer and the investigator found had been erected by family members to memorialize George Jacobs, a Muscogee Creek tribal member. His killer, Murphy, also a member of the Muscogee Creek Nation (MCN), had been living with Jacobs’s ex, Patsy Jacobs. At about 9:30 p.m. on August 28, 1999, Murphy and his friends forced George Jacobs’s car off the road; Murphy then cut his throat and sliced off his genitals, leaving him to die on the roadside.

In 2000, an Oklahoma jury sentenced Murphy to death. Oklahoma appellate courts affirmed the sentence.

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Murphy’s main ground of state appeal was his claim that he suffers from an intellectual disability. (Under Supreme Court precedent, an intellectually disabled defendant cannot be executed.) But the state courts held that he hadn’t proved the disability. Next, he filed a federal habeas corpus petition. The case was assigned to the federal public defender’s office for the District of Oklahoma. The federal-public-defender lawyer to whom it came, Lisa McCalmont, was a noted legal foe of the death penalty; she was also a geologist, and understood the complexity of mineral rights and land titles. She realized that Oklahoma might not have had jurisdiction over the crime.

Oklahoma is second only to California in its number of Native American residents. Before statehood, it was originally called “Indian Territory.” The tortured history of Indian removal, the later assault on Native ownership of land when Oklahoma became a state, and the abundance of oil and gas resources under the soil have created there a complex patchwork of parcels of state territory, federal land, and what is called, under a federal statute, “Indian country.”

The legal term Indian country refers to three kinds of land: existing Indian reservations, “dependent communities” (such as housing projects) maintained off of a reservation by the federal government for the benefit of recognized tribes, and remaining Indian allotments. Allotments are parcels of land that were originally part of reservations. During the late-19th and early-20th centuries, the federal government decided to break up the reservations. It sold small parcels to tribal members, and transferred “surplus” reservation land to non-Indians. During the allotment era, tribes lost more than 60 percent of their land base. But some allotted land is still owned by the original Native families; under the law, that land remains Indian country.

McCalmont, the federal defender, thought that the new crime scene might still be part of an Indian allotment. Research revealed that it had originally been allotted to an individual member of the MCN. In 2004, one of that member’s descendants still maintained a small ownership interest—one-twelfth of the subsurface-mineral rights.

That ownership might make it Indian country, and that possibility has implications for Murphy’s case. An 1885 federal statute called the Major Crimes Act governs most serious crimes committed in Indian country. Indian people charged with these crimes fall under exclusive federal jurisdiction. If the crime scene was Indian country, the state would have had no authority to try Murphy, and his conviction would have to be set aside.

Murphy went back to court with that claim and another: Even if the road was not allotment land, the petition argued, it was still Indian country. Why? Because, the lawyers argued, all the surrounding land was still part of the huge MCN reservation guaranteed under an 1832 treaty with the United States.

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In November 2017, the U.S. Court of Appeals for the Tenth Circuit agreed.

After 175 years, it held, the Creek Reservation remained intact.

How can that be? In 1832, President Andrew Jackson pushed through the policy of “removal” of Indian nations from the eastern U.S., which destroyed the historic land base of the “civilized tribes.” He promised the tribes new land in the West to be theirs “as long as the grass grows or the water runs, in peace and plenty.” After the Trail of Tears, the U.S. signed a treaty that “solemnly guarantied” the new reservation lands in what is now Oklahoma.

Many tribes elsewhere have found to their regret that Congress is permitted to decide that the grass ain’t growing any more. It can abrogate some or all treaty obligations—and even “terminate” a tribe altogether. But case law says there is a “clear statement” rule: If Congress wants to end a reservation, it has to say so.

It apparently did not. The Tenth Circuit said it couldn’t find any statute ending the reservation created by the Creek Nation’s treaty of 1832. Nor could it find evidence that Congress at any time showed a desire to abolish the reservation. Applying a 1983 precedent called Solem v. Bartlett, the court reasoned that all 3 million acres, whether owned by Indians, non-Indians, the federal government, or state or city governments, remained “Indian country.” Under the Major Crimes Act, Murphy’s conviction was void and he was entitled to a retrial in federal court.

Chief Judge Timothy Tymkovich, in a separate concurrence, agreed that the Solem opinion required the court to hold against Oklahoma. However, he said dryly, the high court might want to look at Solem again. “This challenging and interesting case makes a good candidate for Supreme Court review,” he wrote. The Supreme Court granted certiorari in May.

Before the Court, Oklahoma argues that the contemptuous treatment of the tribe by the state and federal government after allotment makes a formal statute unnecessary. “Congress’s breach of its treaty promises of communal land ownership … and tribal self-government, combined with the creation of Oklahoma, amply overcomes the presumption that Congress does not lightly abrogate its treaty promises or diminish a reservation,” the state argues.

Supporting Oklahoma in an amicus brief, the federal government notes that Congress “broke up the Creek Nation’s lands, abolished its courts, circumscribed its governmental authority, applied federal and state law to Indians and non-Indians alike in its territory, provided for allotment of almost all of its communal lands to individual tribal members, distributed tribal funds to individual Indians, and set a timetable for dissolution of the Tribe.” Thus, “Congress did not intend for the new State of Oklahoma to include a massive Creek reservation throughout which the Tribe and the federal government would have jurisdiction to the exclusion of the State over all crimes involving Indians.”

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The problem with this argument is that two years ago, in a case called Nebraska v. Parker, the high court unanimously reaffirmed the Solem rule, and held that Congress and only Congress has the power to diminish or abolish a reservation—and “its intent to do so must be clear.” Two new justices have joined the Court since then. One, Brett Kavanaugh, was opposed by many Native advocacy groups; the other, Neil Gorsuch, was praised by the same groups for his decisions on the Tenth Circuit—and has hired for this term the high court’s first-ever Native American clerk, a member of the Chickasaw Nation. Even for a Court that seems impatient of precedent, though, reversing a unanimous decision from two years ago would be a heavy lift.

The MCN, let’s remember, didn’t start this fight, but it wants to win. “This is a very important case for the nation,” Kevin Dellinger, the attorney general of the MCN, told me. The tribe regards the reservation as a living link with the ancestors who lost their land in the East, he said.

The tribe—and the National Congress of American Indians, in an amicus brief—argues that recognizing the reservation won’t mean an apocalypse. Many non-Indian communities, including a good chunk of Tacoma, Washington, exist within reservation boundaries. Life for non-Indians living in such places is all but indistinguishable from life off the reservation. “The impact on non-Indians would be minimal,” Dellinger said.

Stephen Greetham, a special counsel to the Chickasaw Nation, another Oklahoma tribe, said in a recent seminar about Carpenter v. Murphy that overlaps between state and reservation jurisdictions “have been fundamental to Indian law for decades.” Indian tribal courts have no jurisdiction over civil disputes between non-Indians, he pointed out; indeed, most disputes between tribal governments or members and non-Indian people or companies must be heard in state court. A 2005 federal statute already permits the state of Oklahoma to implement federal environmental laws in Indian country. Other regulatory matters—Indian gaming and casinos, or sales, tobacco, and gasoline taxes—are often covered by compacts between state governments and Indian tribes. “Oklahoma has an enormous amount of experience at this,” Lindsay Robertson, a law professor at the University of Oklahoma, told me in an interview.

Movies and TV sometimes portray reservations as areas where state law enforcement cannot reach. But many tribes sign “cross-deputization” agreements that allow state law-enforcement agencies to operate on reservation land just as they do outside it. Under such an agreement, Oklahoma police would be able to arrest anyone violating the law, Indian or non-Indian.

Granted, trying those arrestees is a different matter. Under the Major Crimes Act, Indians who commit serious crimes in Indian country must be tried in federal court. So the only recourse in a case like Murphy’s is for the U.S. Attorney’s Office in Oklahoma to take over prosecution. Robertson, the law professor, noted that this would mean “a huge expansion in caseload” for the federal agency, requiring additional funds and more prosecutors.

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The alternative would be a congressional statute allowing Oklahoma state courts jurisdiction over major Indian-Indian crime. Whatever the solution, however, a number of existing convictions under state law would theoretically be rendered invalid. In its petition for review, Oklahoma argued that “the Tenth Circuit’s decision raises the specter that hundreds or thousands of state convictions involving tribal members in the eastern half of Oklahoma will be subject to collateral attack.”

Federal habeas corpus petitions, however, must usually be brought within a year after conviction. Oklahoma state courts, too, have a doctrine barring challenges that have been delayed for years. Robertson said the state’s fear may be overblown—especially since there is “the strong possibility that even if granted on federal retrial the sentences would be more severe.” For that reason, “I’m skeptical that many would choose to seek or be able to obtain a retrial.”

If the Tenth Circuit’s decision stands—and if courts restore the reservation boundaries for all five civilized tribes—roughly half of Oklahoma will become, at a stroke, Indian country. Although it’s understandable that Oklahoma wants to prevent this complicated outcome, the state’s argument against the tribes is nonetheless a troubling one. In essence, it says, if Congress and the state have showed contempt for tribes over the years, that alone disestablishes the reservation. It is a bit hard to square that idea with the promises made to the tribes when they were moved from their historic territory to land that would be theirs “as long as the grass grows or the water runs.”

Dellinger, the tribal attorney general, said that recognition from the Supreme Court would be “a big psychological victory” for the roughly 80,000 members of the MCN. Oklahoma’s argument is the mirror image of the tribe’s. Recognizing the reservation, the state’s brief argues, “would shock the 1.8 million residents of eastern Oklahoma who have universally understood that they reside on land regulated by state government, not by tribes.”

The irony here is patent. That shock—finding their community involuntarily transferred to an unfamiliar sovereignty—has been, for half a millennium, the central fact of Native American history.