When can a civilian use physical force on someone? Are there any other times besides in self defence? Is it legal to use physical force in the event of an emergency, for example if you shove someone out of the way of a car and they end up falling and breaking their ankle, can you get sued?

What if you see someone running out a store and people running after them, so you grab them, but it turns out they weren't actually robbing anything?

Interesting story: I was on a bus and an altercation occurred between the bus driver and someone who got on with an expired ticket or something like that. It started by arguing, but then the bus driver shoved the passenger off the bus. Then the passenger punched the bus driver hard in the face. Then it was a full fight. The police arrived and put the passenger in handcuffs, and it seemed like witnesses took different sides as to who started it.

Was it legal for the bus driver to shove the passenger off the bus for not paying? Was it self defense that the passenger hit the driver back? I know some bus companies have policies telling the drivers not to get physical, just call the police if there's a problem.


Battery – offensive, nonconsensual contact with another person – is a crime unless it is justifiable. There are numerous justifications, and the standards for them can vary.

For example, is a justification for battery, and the standard is usually the "reasonable person." I.e., would a reasonable person in the position feel that force was necessary to defend against imminent injury, and was the force used reasonable and proportional to the perceived threat?

Force can be used to effect a lawful . The standards for arrest are different for police officers. For example, police typically need only have "probable cause" (i.e., a justifiable belief that a person likely committed a crime) to effect an arrest, and at the point police are typically allowed to use any force necessary to effect the arrest. On the other hand, "citizens' arrests" are typically limited to more serious suspected crimes and, in practice if not in theory, subject to higher levels of scrutiny.

So, for example, a cop grabbing the person being chased from a store would almost certainly be immune to charges of battery. A bystander doing the same thing would have to be prepared to justify his interference in civil, if not criminal, court.

Some jurisdictions accord a higher right to use force to owners of property. For example, "shopkeeper's privilege" allows merchants to use reasonable force to detain individuals they reasonably believe to have stolen from them. "Castle doctrine" allows people to use lethal force against any intruder in their residence.

In the bus fare scenario you describe the bus driver is guilty of battery. Even if a prosecutor declined to charge him for the crime, the victim of that battery could sue the driver civilly. Likewise, the passenger who chose to subsequently attack the bus driver is guilty of battery, because (presumably) there was no ongoing physical threat once he was off the bus.

  • I would assume that in most if not all jurisdictions a property owner or a person with some interest in property, e.g. a tenant, (i.e. land) can legally use some level of force to remove a trespasser. – bdsl Sep 8 '17 at 22:57
  • @bdsl - Aside from the explicit rights to assault and batter trespassers being enumerated in many "Castle doctrine" laws, I can't offhand think of any laws that justify "forcible removal of a trespasser," though it does seem like something that should exist. That would make a good question here! – feetwet Sep 8 '17 at 23:54

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