_{Map of the Indian and Oklahoma territories. (Library of Congress)}

The Supreme Court considered on Tuesday whether much of eastern Oklahoma is an Indian reservation, a question that could have enormous consequences for the area’s 1.8 million residents in matters of criminal justice and commerce.

The argument was made up of equal parts history, much of it dark, and an assessment of the practical implications of a ruling that Congress had never clearly destroyed the sovereignty of the Muscogee (Creek) Nation over the area, covering about half the state.

The case, Carpenter v. Murphy, No. 17-1107, arose from the prosecution in state court of Patrick Murphy, a Creek Indian, for murdering George Jacobs in rural McIntosh County, in east-central Oklahoma.