Prior to 1869, law enforcement on Indian reservations was the prerogative of the military. In 1869, some Indian agents appointed Indians as law enforcement officers, even though this policy did not enjoy the official sanction of Washington bureaucrats. Sentiment for the use of Indians as law enforcement officials increased, however, until in 1879 Congress recognized the need for Indian police and appropriated funds for such a force. Initially, the police forces were established to maintain law and order among the native inhabitants; however, the modern Indian police have the additional responsibility of protecting inhabitants from external threats. Case law has established that Indian tribes hold and occupy the reservations with the assent of the United States and under the authority of the Federal Government. The Indians' exercise of separate power is constrained so as not to conflict with the interest of the Federal Government's overriding sovereignty. Indian tribes therefore necessarily give up their power to try non-Indian citizens of the United States, except in a manner acceptable to Congress. There is no evidence that this legal posture has influenced any increase in non-Indian crimes on reservations, but it is for Congress to decide whether Indian tribes should finally be authorized to try non-Indians. Eleven references are listed.