In Psychology there is what is called "legalism' not to be confused with legal or illegal. Legalism is where someone deceides that something is wrong and will go to extreems to enforce his oppionion on others, reguardless of wheather the other person is in the right or not.

Examples of this are vigilanties lynching people. There is of course the problem people being not involved enough either as when a murder is witnessed by a group of people and no one will interviene, call the cops or later testify in court.