Police

Police are local, regional, or national governmental personnel who are responsible for investigating crimes and arresting criminal suspects, reducing the incidence of criminal acts, managing vehicular traffic and responding to accidents, and a variety of emergency services dependent on local needs and policies. They are principally responsible for domestic criminal matters, although certain police agencies may have anti-terrorist or paramilitary roles.

Again depending on local law and custom, they may operate prisons, but will almost always have temporary secure holding facilities, often called jails, for suspects.

Investigative functions

While it may be immediately obvious who committed a crime, it also may be quite difficult to determine the perpetrator, and specialists called detectives or criminal investigators may become involved in the inquiry. Increasingly, forensic techniques, involving the use of scientific techniques to discover and characterize evidence.

Investigators may specialize in certain types of crimes, such as murder, sexual offenses, drug abuse, forgery, etc.

Civil rights

The role of the police towards civil and criminal rights varies widely. In some case, police may actively investigate and enforce civil rights violations. They may be constrained by rules in how they may interrogate prisoners and collect evidence.

In some countries, however, "secret police" or "political police" may be among the worst violators. Gestapo, derived from the German (originally Prussian) "secret state police" has become synonymous with abuse.

Specialized jurisdictions

Military police may have authority only over military personnel, but often have role in maintaining order in occupied areas after combat troops have left. In the Iraq War, military police often escort convoys and can take on a combat role very much like that of infantry.

Sheriffs and deputy sheriffs may be police officers who are responsible to the courts, maintaining order and security, and carrying out judicial functions such as serving court orders.