Cop. Sheriff. Trooper. They each carry a badge and a gun. They take an oath to protect and preserve the peace. On the surface, it would seem that the terms are synonymous with “law enforcement officer”. But, in fact, these uniformed men and women hold distinct jobs.


Here’s a short list of different law enforcement agencies that you should be aware of.

State Police: Most people think of them as highway cops who give tickets, but they oversee much more than that.

County Police: Depends on the area. They may be the official, full-service police department for an entire area – or they may provide service for the smaller towns that cannot afford their own police force. Additionally, county officers may be stationed to keep certain government offices secure, like a courthouse.

Sheriff: If no local or county departments exist, then the sheriff’s department provides full law enforcement services. Otherwise, the sheriff is mainly responsible for serving warrants and transporting prisoners between court and jail.

Municipal Police: Major cities and most mid-and large-size towns maintain their own police department to handle local crime.

Campus Police: A police department that is run by a state or private university or college. The officers have gone through official police academy training and are fully sworn. Oftentimes, Campus and Municipal Police will have a Memorandum of Understanding in place that requires the school to turn over all major crime investigations to the local police.

School Resource Officer: A sworn police officer assigned by the local police department to a public school.

Correctional Officer: Formerly called “prison guards” but now shortened to “CO”, this title is a misnomer. Correctional officer do not take an oath to uphold public safety and they do not have arrest powers. While they’re trained to use guns, they are not issued personal weapons that they become responsible for on- and off-duty.

Special Police: A citizen who meets basic police standards and is certified through the State Police to carry a gun. Special Police have arrest powers under certain conditions.

Security Guard: A citizen who works for a private company and provides an extra set of eyes and ears to be on the lookout for crime and to help keep peace in an area they have been hired to patrol. Despite any badge they may have, guards have no arrest power and have no authority to detain anyone.

Park Rangers: Enforces rules and regulations in parks. Rangers are not sworn officers and have no arrest powers.

In addition to local and state police, the federal government also maintains a large cadre of law enforcement agencies. The US Marshal dates back to the late 1700s. They’re best known for 2 jobs: Tracking down violent offenders who are on the run; and Running the Witness Protection Program.

Other Federal law enforcement agencies include:

  • Military Police
  • Postal Police
  • Drug Enforcement Agency (DEA)
  • Federal Bureau of Investigations (FBI)
  • Central Intelligence Agency (CIA)
  • U.S. Park Police
  • Natural Resources Police

Having a clear idea of setting will help you know which agency or individual will first respond to a scene. Having a clear idea of the crime committed will then help you know if other agencies will be called in to help with the investigation.

For example, if an incident takes place inside a grocery story, either a security guard or a special police officer may be on duty and will respond first. Security guards would probably carry pepper spray, but special police officers will have a gun. If an arrest needs to be made, the local police will be called to verify the legality of the arrest. They would then respond to the scene to transport the individual to jail.

If, however, the grocery store is on a military base, then only military police will respond to the incident – even if it involves a civilian. Military bases are considered federal property. No local town, city, county, or state police have any authority to enter a military base, let alone arrest someone for a crime committed on the base.

The key to writing about law enforcement is understanding jurisdiction. Just because a person carries a badge and gun does not mean they have the authority to pursue a criminal or investigate a crime if the crime is outside their zone of authority. This issue comes up in many different situations, including high speed chases that cross county and state lines.

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Written by Nic

A veteran law enforcement officer with 26+ years of experience, Sgt. Nicodemus consults with writers looking for a more authentic voice in their fictional crime writing.

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