Let The Punishment Fit The Crime

Granted in a real-life self-defense you don't really have time to think about what you're doing, you still have to use that most important weapon: the brain. Especially in today's society where people sue first and ask questions later, and you're just as likely to be arrested for defending yourself as the guy who just tried to rob you, you have to be conscious about how you choose to defend yourself. The simple maxim I use is that the punishment should fit the crime. Just like a judge or jury would give a first-time car thief life in prison (this is of course assuming stealing the car was all that he did!), you shouldn't rake someone's eyes out and cause potentially permanent damage when they're just drunk and simply being a little extra flirtatious. By all means, if your life is truly in danger, then do whatever it is you have to do to survive, but be prepared to justify your actions afterwards.