DERRICK JAMES | Staff photo More than 140 cases have been filed in Choctaw Nation District Court in Durant since April 1. The Choctaw Nation Division of Legal and Compliance answers questions following an April 1 decision by the Oklahoma Court of Criminal Appeals in Sizemore v. Oklahoma, a case originating in Pittsburg County, applying a U.S. Supreme Court decision in McGirt v. Oklahoma to the Choctaw Nation. 1. What is the Sizemore decision? It is a ruling from Oklahomaâs highest criminal appeals court that the Choctaw Nationâs 1866 reservation boundaries were never changed, therefore land within those boundaries constitutes a reservation and is Indian Country. Therefore, Indians who commit crimes on the reservation must be tried in either federal court or Choctaw Nation court and not state court. Non-Indians who commit certain crimes against Indians on the reservation may also be tried in federal court or in Choctaw Nation court.Â