What is Posse Comitatus?

Mary McMahon
Mary McMahon

Posse comitatus is a concept in common law which states that law enforcement officials may conscript able-bodied individuals, classically limited to men, for the purpose of specific law enforcement tasks. While many nations technically permit posse comitatus to occur, it is extremely rare to see law enforcement conscripting civilians, despite the depictions in Western films and novels. The term “posse comitatus” is also used in reference to the Posse Comitatus Act of the United States, which explicitly forbids the use of American military forces for law enforcement activities, with the exception of the Coast Guard.

Both sides in the English Civil War could conscript civilians to fight for their cause.
Both sides in the English Civil War could conscript civilians to fight for their cause.

This common law concept is centuries old, dating back to a time before law enforcement was viewed as a highly specialized task which required unique training. Sheriffs could muster up able-bodied men to keep the peace during periods of civil unrest, to seek out criminals, and to provide additional security as needed. The posse comitatus concept was sometimes invoked by opposing sides, as seen during the English Civil War, in which both sides had the ability to conscript civilians.

Law enforcement officers are more likely to commandeer vehicles, another grossly-exaggerated law enforcement power, than they are to conscript civilians, due to safety issues. Civilians are not trained to participate in law enforcement tasks, and they could endanger themselves or others if they were impressed into a posse. In emergency situations where law enforcement officers do start deputizing civilians, they will likely seek out retired law enforcement and people with military experience.

Under the Posse Comitatus Act, members of the American military cannot be pressed into service for law enforcement tasks. One of the key ideas behind the act was that its architects did not want to see the American military working domestically, and the act was also designed to limit the powers of the federal government. In point of fact, members of the National Guard and Coast Guard are used for law enforcement tasks in the United States and abroad, leading some people to suggest that this Act should probably be revised to reflect the shifting nature of the United States military.

Thanks to the frequent use of the posse comitatus as a plot device in Westerns, many people refer to a group of individuals conscripted by a law enforcement officials as a “posse.” The term “posse” has also come to be used more generally used to refer to a group rallied around a single individual or cause.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Civilians are sometimes still deputized by a county Sheriff or other law enforcement officer, even in times with no specific unrest or mission. Many counties have reserve deputies who are civilians except when on duty. The famous (or infamous) Sheriff Joe in Maricopa County, Arizona, even refers to his reserves as a "posse".

I have never heard of involuntary conscription of civilians for something like that, though. I would be very nervous of cop who was "drafted" and didn't even want to be there having any kind of power over people.


One exception to the Posse Comitatus law was the City of New Orleans right after Hurricane Katrina. After days of riots and disorder, with rescue and repair workers unable to get to people because they were being shot at, even the National Guard was not enough to stop the violence.

The President sent in the 82nd Airborne to patrol parts of the city. You could see them on the news walking in formation through the city with their rifles and maroon berets. It was a very powerful image, and it helped to bring order to the city, but it is understandably used very seldom. I don't think using the military for law enforcement is a very good idea generally, and fortunately neither did Congress, so they passed this law.


@JaneAir - the Coast Guard has always been a little different in how they are treated. Certain personnel are considered Federal law enforcement when they are on duty doing specific tasks like boarding parties and drug interdiction.

That is why they are not under the Department of Defense like the Army, Navy, Air Force, and Marines. They used to be part of the Department of the Treasury, and now after 9-11 they are under the Department of Homeland Security. In time of war, they can be attached to the Department of Defense.


@JaneAir - That sounds reasonable to me.

However, I'm very glad that police officers don't just go around conscripting people to act as law enforcement anymore. Being a cop is a specialized job that you have to have training for. Most civilians definitely couldn't just go do that job without extra training.

I also think it's funny so many movies show police officers commandeering people cars. I've never, ever heard of this happening in real life!


My stepfather is in the Coast Guard and he was actually just explaining this concept to me the other day. The Coast Guard actually has a lot of various duties that range from search and rescue to doing drug busts on the open water.

I think the fact that the Coast Guard does so many different things is the reason why it works to have them work as law enforcement. Unlike the other branches of the military, the Coast Guard's primary job is to guard and protect our borders. So it seems logical to me that they should have some law enforcement privileges.

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