American policing is highly decentralized. There is no national police force, and most officers work for agencies with fewer than 50 employees. Policing reflects local priorities and politics, which produces wide variation in practices, training, and accountability across the country.
This guide explains who polices what, who controls the police, the legal limits on them, and the debates over reform.
Since 1994 the Justice Department's Civil Rights Division has had authority to investigate departments with a pattern or practice of unconstitutional policing and to seek court-enforced consent decrees, used in cities such as Los Angeles, Chicago, and Baltimore. The federal government also funds local policing through grants and supplies surplus military equipment. In 2025 the Justice Department ended several pending reform agreements, including in Minneapolis and Louisville, and in August 2025 the President invoked a provision of the District of Columbia Home Rule Act to place the city's police under temporary federal direction and deployed National Guard troops in the capital.
Municipal police chiefs are usually appointed by mayors or city managers and answer to elected officials. County sheriffs are elected in nearly every state, giving them independent political standing, and they typically run county jails, serve court papers, and patrol unincorporated areas. Some sheriffs have publicly refused to enforce state laws they consider unconstitutional, and sheriffs have taken differing approaches to cooperating with federal immigration enforcement.
The Bureau of Justice Statistics counts about 18,000 state and local law enforcement agencies, including city and town police, county sheriffs, state police, and special agencies for transit, schools, campuses, parks, and airports. About half employ fewer than 10 full-time officers, while the largest, the New York Police Department, has more than 30,000. Tribal police serve many reservations. Because the Constitution leaves the general police power to the states, most crimes are investigated and prosecuted locally.
Most states have a state police force or highway patrol, which enforces traffic laws on highways, assists local agencies, and in some states investigates major crimes. State attorneys general and state investigative bureaus handle statewide cases. Federal agencies such as the FBI, DEA, ATF, and U.S. Marshals enforce federal law and often work with local police through joint task forces. Local police may assist federal immigration enforcement through 287(g) agreements, which expanded sharply in 2025.
The Fourth Amendment bars unreasonable searches and seizures, Miranda v. Arizona in 1966 requires warnings before custodial interrogation under the Fifth Amendment, and the Sixth Amendment guarantees counsel. The 14th Amendment applies these protections to state and local police. People whose rights are violated can sue under a Reconstruction-era federal law, but the judicial doctrine of qualified immunity shields officers unless they violated clearly established law, a doctrine that supporters say protects officers' split-second decisions and critics say blocks accountability.
After the killing of George Floyd in Minneapolis in 2020, many cities and states adopted reforms such as bans on chokeholds, body camera requirements, and civilian oversight boards, and some cut police budgets before reversing course as crime rose. Federal legislation stalled in Congress. Homicides fell sharply in 2024 and 2025 from their 2021 peak. Supporters of stronger policing emphasize public safety, officer recruitment, and support for police, while reform advocates emphasize accountability, civil rights, and alternatives for mental health calls.
See the federal agencies in federal law enforcement agencies, learn about the Guard in the National Guard explained, or see the local governments that run police in how local government works.