Many people think that everyone involved in the criminal justice system are "bad" people who are intentionally breaking the law. This misconception makes it hard for the people who have legitimate underlying problems that led them to face criminal charges.
You have the right to defend yourself or others from attack
Security is far from a given these days. People can find themselves in danger while shopping, at a movie theater or even during a walk outside. You could be the unintentional victim of a would-be mugger. Perhaps you witness someone mercilessly beating someone else. Maybe you run into someone you have had a bad interaction with in the past, and things turn violent.