“The holding of McGirt is that this land, which has 1.8 million residents, most of whom are not Native American, is reserved land. Oklahoma must honor a treaty from nearly two centuries ago setting aside this land for Native peoples.”
…
“The primary impact of McGirt is that Oklahoma loses much of its power to enforce certain laws against members of Native American tribes within the borders of tribal lands. But the decision will have far less impact on non-Native Americans.”
…
“The fact that McGirt is a member of a tribe, and that his crime took place on a reservation, matter because of the federal Major Crimes Act (MCA). That law provides that “any Indian who commits” certain offenses “against the person or property of another Indian or any other person” is subject to “the exclusive jurisdiction of the United States” if that crime was committed “within the Indian country.”
Thus, Oklahoma lacks authority to try McGirt for raping someone on a Native American reservation. Only the federal courts may try such a crime.
On the surface, in other words, McGirt seems to involve a fairly minor issue. No one questions that McGirt may be convicted of rape. And no one questions that he can face a stiff penalty for such a conviction. The question is which court may try the case against him.”
…
“Congress may wipe away its treaties with Indigenous peoples at any time, and it may dissolve a Native American reservation on a whim.
But despite its many incursions on the Creek people’s tribal sovereignty, McGirt concludes that Congress has never taken the ultimate step of dissolving its original treaty with the Creek people. That means that Creek lands remain a reservation — including the place where McGirt committed his crime.
And that means that McGirt must be tried in federal court.”
https://www.vox.com/2020/7/10/21318796/supreme-court-mcgirt-oklahoma-native-american-neil-gorsuch