It's a scene you've probably seen in movies or television shows: an intrepid pedestrian shouting, "Citizen's arrest!" and dramatically pummeling a criminal to the ground while onlookers clap. But chances are you haven't seen it in real life. The reason? Citizen's arrests can be dangerous and their legality varies by state. So if you've ever fantasized about being a real-life hero, read up so you're ready should the perfect opportunity present itself. 

The first thing to remember is that in the term “citizen’s arrest,” the word “arrest” refers to stopping or halting someone, not a formal police arrest. You’re not responsible for reading Miranda Rights and bringing the perpetrator down to the station. The purpose of a citizen’s arrest is detaining a criminal until the proper authorities arrive. 

New York Penal Law §35.30(4) states:

A private person acting on his or her own account may use physical force, other than deadly physical force, upon another person when and to the extent that he or she reasonably believes such to be necessary to effect  an arrest or to prevent the escape from custody of a person whom he or she reasonably believes to have committed an offense and who in fact has committed such offense...

In layman’s terms, you’re allowed to detain a criminal if you reasonably believe it’s necessary to prevent their escape, if you reasonably believe they committed a crime, and if they actually have committed the crime. Many states also recognize “Shopkeeper’s Privilege” under which the proprietor of a store is allowed to detain a would-be shoplifter for a reasonable period of time.

Although the actual statutes vary state by state, most common law interpretations require that the citizen who’s making the arrest actually witnessed the public offense taking place. This is also important considering a citizen making an arrest doesn’t get the same protection a police officer does if they make a mistake: Police can detain anyone for reasonable suspicion; someone making a citizen’s arrest can get sued or arrested for making a false arrest.

Jerome McHenry, the owner of a private security firm in California, detailed the process of making a citizen’s arrest in the New York Times Magazine. "Speak in a stern, matter-of-fact voice," he said. You should announce your intent clearly and loudly: "You’re under citizen’s arrest.” 

Most states permit the use of necessary force, but be sure that you’ve sized up the situation properly. Don’t make a citizen’s arrest if it puts you, or anyone else on the scene, in more danger. As the New York Times Magazine wrote, “It is always better to be a good witness than to botch an arrest, thereby endangering yourself and further complicating an unfolding crime.” 

So study up your state laws, and should you ever see a purse-snatcher, know the extent to which you can play superhero—at least until the police come. 

[h/t New York Times Magazine]