Indian agency police were policemen hired by United States Indian agents during the late 19th and early 20th centuries and assigned to a Native American tribe. It was the duty of Indian agency police to enforce federal laws, the laws of the state where their reservation was located, and the terms of the federal treaties with their tribal authority.

The very first Indian police made their appearance in the Great Plains in the 1830s. This was partly due to the relocation of tribes such as the Cherokee into Indian territories.^[1]

Many tribes had no recognizable governments and therefore no tribal laws. On these tribes' reservations, the Indian agent hired tribal members to effect law and order according to federal, agency, and treaty rules.

Some tribes, such as the Cherokee, had well-developed systems of tribal laws and tribal courts; the agency police also enforced these laws, and they testified and maintained order in the tribal courts. Since the agency police were federal officers, crimes against them had to be tried in a United States district court.

Indian policemen had a wide range of responsibilities, such as maintaining law and order, protecting agency property, arresting offenders, managing jails, and serving as messengers. They also patrolled reservation boundaries, detaining thieves and enforcing various bans.^[1]

Unfortunately, they often faced danger, with at least twenty-four officers losing their lives in Indian Territory alone between 1876 and 1906. The deadliest incident occurred on December 15, 1890, when six members of Standing Rock's Indian police force were killed while trying to apprehend Sitting Bull. They were responsible for the death of Sitting Bull and 12 other Native Americans, which has resulted in an unfavorable view by historians.^[1][2]