Drjones, if stopping a violent crimes results in the perp's death, too bad? Well, it may be too bad for you as well, either as a murder charge or manslaughter if you used lethal force for a situation where the use of lethal force is not valid legally. You are going to have trouble justifying why you beat a man to death who was simply trying to snatch a purse from an old lady who would not let go. It would be a violent crime, but not one necessarily that would allow for lethal force.
From what I have seen in the papers (not legally binding concepts, of course), vigilantism seems to be viewed as the over-use of force to stop a crime or the inflicting of additional harm on the perp after the crime has been stopped and the perp isn't trying to commit another (like assaulting the heroes who stopped him). For example, it would be very hard to justify shooting some guy because he was dumpster diving in your apartment complex which was an act illegal in your area. Vigilantism often involves bypassing due process and formally or informally providing punishment for the crime after it has stopped.
Also, there is nothing wrong with going out and looking for trouble as a witness. HKmp5sd sort of brought this out. There are a variety of neighborhood watch groups and such who do this exact thing, look for trouble. The difference is that they are only serving the role as witnesses and are not likely to actually intervene unless somebody's life is in peril. Their job is to simply report the crimes to the police in conjunction with being a good witness and recording salient information.
Self defense is NOT a form of vigilantism, nor is defense of life. However, the families of perps often claim otherwise. Years ago, I saw a show where the mother of a kid involved in a gang initiation group home invasion who was killed by the homeowner kept repeating over and over that the punishment for trespassing was not death and that the homeowner had done wrong. Several kids had broken into the house late one night. Hearing the noise, the homeowner grabbed his gun and spotted several youths in the hallway that led from the main living area of the house to the bedroom area which contained himself, his wife, and his 2 kids. He yelled at the intruders to get out. Instead, the advanced on the guy. The 911 recording of the event documented at least twice that the guy ordered the boys out, followed by shouting (the intruders), and then gun shots. He killed the lead boy from a distance of less than 5 feet. The rest scattered. The mother of the dead youth could not understand why the homeowner was not in jail for murder since he killed her unarmed "child." She was quick to note that the homeowner was much larger than her child and could have stopped him by hand. She neglected the fact that her son was one of at least 8 youths in the house at the time and that the homeowner was outnumbered. Of course, the homeowner was never even charged with a crime.
Here it is important to point out that after stopping the youth, the home owner did not then adimister additional gun shots or punishment such as beating. That would have been vigilantism since it would have been after the fact. His acts stopped when the threat stopped...which is self defense.
Contrary to what the mother of the dead youth may think, in many parts of the country, lethal force is considered perfectly legal for "trespassing" in another's home in the middle of the night.
