Law enforcement in the United States

Law enforcement in the United States is one of three major components of the criminal justice system of the United States, along with courts and corrections. Although each component operates semi-independently, the three collectively form a chain leading from an investigation of suspected criminal activity to the administration of criminal punishment.

Law enforcement operates primarily through governmental police agencies. There are 17,985 U.S. police agencies in the United States which include city police departments, county sheriff's offices, state police/highway patrol 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, to varying degrees at different levels of government and in different 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; the maintenance of public order; the protection of public officials; and the operation of some detention facilities (usually at the local level).