Internal Affairs (law Enforcement)

The internal affairs (United States terminology) division of a law enforcement agency investigates incidents and plausible suspicions of lawbreaking and professional misconduct attributed to officers on the force. In different systems, internal affairs can go by another name such as "Internal Investigations Division" (usually referred to as 'IID'), "professional standards," "inspectorate general", Office of Professional Responsibility or similar. Non-internal affairs officers often derisively refer to the departments as the "rat squad."

Several police departments in the USA have been compelled to institute civilian review or investigation of police misconduct complaints in response to community perception that internal affairs investigations are biased in favor of police officers. For example, San Francisco, California, has its Office of Citizen Complaints, created by voter initiative in 1983, in which civilians who have never been members of the San Francisco Police Department investigate complaints of police misconduct filed against members of the San Francisco Police Department. Washington, DC, has a similar office, created in 1999, known as the Office of Police Complaints.

Due to the sensitive nature of this responsibility, in many departments, officers working internal affairs are not in a detective command, but report directly to the agency's chief, or to a board of civilian police commissioners.

Internal Affairs investigators are bound by stringent rules when conducting their investigations. In California, the Peace Officers Bill of Rights (POBR) is a mandated set of rules found in the Government Code.