Law enforcement in the United States

As of 2020^[update], more than 900,000 sworn law enforcement officers have been serving in the United States. About 137,000 of those officers work for federal law enforcement agencies.^[1]

Law enforcement operates primarily through governmental police agencies. There are 17,985 police agencies in the United States which include local police departments, county sheriff's offices, state troopers, and federal law enforcement agencies. The law enforcement purposes of these agencies are the investigation of suspected criminal activity, referral of the results of investigations to state or federal prosecutors, and the temporary detention of suspected criminals pending judicial action. Law enforcement agencies, are also commonly charged with the responsibilities of deterring criminal activity and preventing the successful commission of crimes in progress. Other duties may include the service and enforcement of warrants, writs, and other orders of the courts.

Law enforcement agencies are also involved in providing first response to emergencies and other threats to public safety; the protection of certain public facilities and infrastructure, such as private property; the maintenance of public order; the protection of public officials; and the operation of some detention facilities (usually at the local level).

Types of law enforcement agencies

Policing in the United States is conducted by "around 18,000 federal, state and local law enforcement agencies, all with their own rules". Every state has its own nomenclature for agencies, and their powers, responsibilities and funding vary from state to state.^[2] 2008 census data from the Department of Justice's Bureau of Justice Statistics (BJS)^[3] revealed that this constitutes:

73 federal agencies
50 primary state law enforcement agencies
1,733 special jurisdiction agencies
3,063 sheriff's offices
12,501 city, county, tribal, and regional police departments

Federal

At the federal level, there exists both federal law enforcement agencies, which possess full federal authority as given to them under United States Code (U.S.C.), and federal law enforcement agencies, who are authorized to enforce various laws at the federal level. Both police and law enforcement agencies operate at the highest level and are endowed with police roles; each may maintain a small component of the other (for example, the FBI Police). The agencies have jurisdiction in all states, U.S. territories, and U.S. possessions for enforcement of federal law. Most federal agencies are limited by the U.S. Code to investigating only matters that are explicitly within the power of the federal government. However, federal investigative powers have become very broad in practice, especially since the passage of the Patriot Act. There are also federal law enforcement agencies, such as the National Park Service Law Enforcement Rangers, that are granted state arrest authority off primary federal jurisdiction.

The Department of Justice (DOJ) is responsible for most law enforcement duties at the federal level.^[4] It includes the Federal Bureau of Investigation (FBI), the Drug Enforcement Administration (DEA), the Bureau of Alcohol, Tobacco, Firearm