Although both policing and criminal court jurisdictions within Indian country can vary according to the nature of the crime and whether the offenders and victims are Indians or non-Indians, Federal law enforcement agencies clearly have the authority to investigate violations of the U.S. Code on Indian lands that apply to Federal enclaves, crimes specified in the Indian Major Crimes Act, State offenses that are incorporated by operation of the Assimilative Crimes Act, those crimes having a significant Federal nexus, and Federal laws that apply generally throughout the Nation. States also have jurisdiction over crimes on Indian lands based on Federal statutes. Tribal police have a significant role in enforcing and investigating violations of Federal or State law under agreements with the Federal Bureau of Indian Affairs. Regarding court venues for crimes committed on Indian lands, tribal courts are limited to jurisdiction over misdemeanors committed by Indians. Tribes that do not have tribal courts typically have courts that operate under Title 25 of the Code of Federal Regulations, Section 11.300 (CFR courts). State courts, in some instances, may have concurrent jurisdiction over both Indian offenders and Indian victims for crimes committed in Indian country. The Federal district courts have jurisdiction over anyone who commits a Federal enclave offense, any Indian who commits a "major" offense under the Indian Major Crimes Act, anyone who violates Federal statutes of general applicability, and anyone who commits a distinctive Federal crime. 55 notes