While at my brother's house in Oklahoma, I picked up one of his paperbacks, Tom Clancy's Without Remorse, in which a Vietnam veteran loses his girlfriend to a vicious drug dealer and proceeds to "clean up" Baltimore's streets as he seeks revenge. Then yesterday, I read the very popular teen fiction book, The Hunger Games, in which a girl is forced to fight to the death against other teenagers in a "game" set up by political overlords to keep the people of outlying districts painfully aware of their status as subjects.
Both books deal with the issue of when it is justified to kill another person. Not a pleasant subject, and one I hope never to have to grapple with personally. I preferred the way this question was answered in The Hunger Games, where the author demonstrates how killing done to protect a vulnerable, innocent other from imminent death can take place without any subsequent guilt. In Without Remorse, the protagonist's decisions to end others' lives are not so clearly justified, and I do not feel that he was a hero or a model of good, or even acceptable, morality; he seemed far more motivated by a desire for vengeance than a desire to protect present and future drug addicts. I cannot accept vigilante justice in a place that has functional police and courts.
We must never be casual about inflicting violence on anyone, but there do exist circumstances which justify the use of deadly force. I support the U.S. Constitution's right to "bear arms" because people need to be able to protect themselves and others from deadly force wielded by criminals. The police can't be everywhere, and there are evil people who seek out "soft" (undefended) targets all over the world. When we stop them from intentionally killing innocent people (yes, I saw the memorial of the Oklahoma City bombing while I was there over Christmas break), we do a good thing.