Most people have heard about “citizens arrest,” which basically lets a citizen, as opposed to a law enforcement officer, arrest people committing a crime until the police arrive. TV shows and movies about crime often portray citizens arrests – usually very inaccurately.

On one end of the spectrum of TV and movie portrayals of citizens arrests is the Chuck Norris situation of a regular guy taking on everyone breaking the law – and using some pretty cool machine guns and explosions to get the job done.

On the other end of the spectrum are TV shows and movies where people are too afraid of the legal consequences of using force and end up getting killed by the bad guys. Those shows are less common because, well, there are no cool machine guns or explosions and hence less of a reason to watch them.

Both ends of the spectrum are myths, at least under Montana law.

Montana has a statute on this topic, MCA 46-6-502. It provides: “A private person may arrest another when there is probable cause to believe that the person is committing or has committed an offense and the existing circumstances require the person’s immediate arrest. The private person may use reasonable force to detain the arrested person. A private person making an arrest shall immediately notify the nearest available law enforcement agency or peace officer and give custody of the person arrested to the officer or agency.”

There are a couple of noteworthy parts to this statute. The first is “probable cause,” which has been described as “it’s at least 51% likely a crime is being committed or has been committed.” “Probable cause” is not the much higher standard of certain of “beyond a reasonable doubt.” This means a private citizen can’t walk up to someone and arrest them when there is no indication that person is committing or has committed a crime.

The second noteworthy part to the statute is that citizens arrest powers apply to a person who is committing or has committed an “offense.” That means felonies and misdemeanors and ordinances with criminal penalties. That would exclude routine traffic tickets. (There is a famous 1963 episode of the Andy Griffith Show where Gomer makes a citizens arrest of Barney Fife for making an illegal u-turn. That wouldn’t work in Montana.)

The third part is that the citizens arrest must occur under circumstances that require the bad guy’s “immediate arrest.” This is a limiting factor in citizens arrests. If an armed bank robber is running down the street, that would require an immediate arrest. If someone is making a u-turn, that would not because the police could handle it. A good rule of thumb is that if you make a citizens arrest you should be able to clearly articulate why waiting for the police would have let a dangerous person get away. In most situations, it’s obvious (like an armed bank robber running down the street).

The fourth part – and this is a big one – is that a person making a citizens arrest can only use “reasonable force.” Pulling a gun is “force”; it’s not just shooting one that counts as “force.” And note that the only “reasonable force” you can use is to “detain” the bad guy. Executing a detained prisoner in the street is not OK.

The fifth part is that “immediately” after the citizens arrest, a person must notify law enforcement. Torturing the bad guy to get him to confess is great in Chuck Norris movies but would not work out well for you in Montana.

The bottom line is that you should not be shy about making a citizens arrest or otherwise defending yourself. Montana has a legal culture that supports self-defense. But be reasonable. If you are trying to live out a Chuck Norris movie, you’ll have trouble with the law. My personal standard for this is “could I live with myself if I did nothing?” and “how would I explain what I did to a prosecutor?”