I was commenting on a story about school bullies, and someone responded to my comment, saying that "since vigilantism will never be legal, we need police to deal with juvenile assaults just as they would with adult assaults". (Except all those committed by the reavers, themselves, I suppose.)
Slow down, Pokey. Self defense is NOT vigilantism. Not by a long shot.
I hate vigilantes. What they do doesn't qualify as self defense, but as revenge or retribution. They are no better than government goons.
Self defense is just the act of stopping yourself from being harmed by someone who is attacking you. That is your responsibility- whether you choose to fulfill it or not. If you fight back against someone who is attempting to steal from you this is defense of property, not of "self". But it is still fine and dandy. Fight back! Don't let bad guys get away with it.
But, once they do "get away", following them to exact revenge is not the best way to deal with it. It is too easy to target the wrong person at this point. If you feel you must anyway, then you accept full responsibility for any mistakes you make and you will be held accountable. As you should be.