Federal jurisdiction in this sense is important in criminal law because federal law does not supersede state criminal law. Congress has enacted the Assimilative Crimes Act (), which provides that any act that would have been a crime under the laws of the state in which a federal enclave is situated is also a federal crime. As most such enclaves are occupied by the military, military law is especially concerned with these enclaves, especially the issue of establishing who has jurisdiction and what type of jurisdiction. In such areas, the federal government may have proprietary jurisdiction (rights as landowner), concurrent jurisdiction (with federal and state law applicable), or exclusive jurisdiction over the land where an act was committed. Courts-martial involving military members subject to the Uniform Code of Military Justice apply regardless of location.