What is the difference between a homeowner defending his life, and a vigilante?

Geek With A .45 has an excellent post up in which he sets us straight regarding defensive use of a gun versus the notion that a legal gun owner is a vigilante. I first encountered this argument 35 years ago. I was having a lunchtime meeting with a lawyer, who happened at the time to work for the prosecutors office. I don't remember how it came up, perhaps discussing current events. I remember what he said to me, though. He said that if I happened to shoot an armed burglar in my house, that he would have to prosecute me for murder. His reason? Because burglary is not a capital offence.

Tilt.

Being in my early 20s then, I was less sure of myself, and of my arguments as I am now. Now I would point out, as the Geek does, that if that were to happen, I would be defending myself, not executing societies judgement on this man. Society may well deem that armed burglary is not a capital offence. But I as an individual do not have the option of waiting to see when my life is being threatened. But as usual, the Geek says it best:

If I should ever wind up shooting someone, it will be because it was necessary to stop them from doing something heinous to me or mine, and not for the purposes of performing summary capital punishment. While the result may be the same, the basis is different.

I am not judge, jury, and executioner. I'm the guy who chooses not to meekly submit his life and well being to the mercy of an aggressor, and the gun in my pocket is a tool with which I can make that stick.

I would also point out that carrying an armament into a place where one has no right to be entails risks, or so the gun grabbers are always saying about legal gun owners. That being the case, one has to assume that anyone engaging in such practices will sooner or later face such risks.