Chairmain Pow:
What you’re talking about is called Legal Self Defense. It is an extremely important and often overlooked part of self defense. It is sadly overwhelming undertaught in martial art schools; which, would be the perfect place to teach it. I’m guessing the reason it is avoided is both ignorance and to further distance the instructor from potential liablity, presumably from his own students who may sue if they get dragged into court after following his advice.
First, I am not a lawyer nor do I play on on TV or message boards. Become familiar with your local laws. For example, almost everywhere attacking an attacker when they are down gives you civil liability and quite likely opens up criminal charges. The law views the first fight as having ended and you initiating a new one.
Martial arts training will, it is not even a case of may, be used against you. Any good lawyer will use every edge they can and they’ll try to protray you as:
a) some hothead martial artist spoiling to try out your skills
b) somebody who should have been able to control the fight
When should you attack/counterattack? First, read “The Gift of Fear”. The answer is that if you have developed the defensive mindset then you can reliably trust your instincts. If things are about to get violent, there is nothing wrong with attacking first. Similarly, when under attack there is nothing wrong with counterattacking, but know your local laws. For example, although this may have been repealed, at one time New York had a law requiring the defender to attempt to escape even if no reasonable means exist.
What do you do when the cops show up? Follow their instructions. View this from the cop’s view. He shows up to see you in combat with somebody. You know you’re the good guy but he has absolutely no idea who is who. So he’ll order you both to stop fighting and get in the ground. He’ll likely put you both in handcuffs. Don’t protest or struggle, let the bad guy do that.
When he comes to get your statement don’t embellish, don’t boast, don’t make stuff up. All of that can hurt you. For example, “He came at me and so I popped him one.” could make you look overly aggressive.
What do you do when you’re sued? Hire a lawyer and bite the bullet. Follow your lawyer’s advice.
What do you do you do when attacked to avoid being sued? Of course the obvious, as above be familiar with your local laws and obey them. However, one very good principle is to look defensive to any witness (they count for alot to the police because they are generally unbiased). So by having your hands up, open, backing away (just a step will do) and yelling “Hey, I don’t want any trouble” you can save yourself any trouble. This creates a jarring image in the minds of any witnesses, and even if you do it just as you attack it’ll appear to them that you were one attacked. Avoid appearing to be the aggressor at all costs. Simpler techniques have an advantage here as well, since they about appear to make you into some “super martial artist” picking on some poor schlub.