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 investigation of suspected criminal activity to administration of criminal punishment. Also, courts are vested with the power to make legal determinations regarding the conduct of the other two components.
Law enforcement operates primarily through governmental police agencies. The law-enforcement purposes of these agencies are the investigation of suspected criminal activity, referral of the results of investigations to the courts, 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.