Bill Romanowski punches teammate Marcus Williams during a fight in practice and breaks the guy's eye socket. Williams, currently on the injured reserve list, might not have a football career to go back to, if he can't see straight.
As martial artists, we could do the same thing to someone else. It's kind of scary, the damage one could inflict, and the legal ramifications of that one punch.
Yet we don't want to hesitate when action is warranted--if you're being attacked, you want to defend yourself with your best weapons. You don't want to slow down, think, "...should I hit him in the jaw, potentially fracturing his mouth, or in the temple, potentially killing him?"
I don't know a good way around this.
A friend related some comments by a mutual acquaintance, who happens to be a member of SFPD SWAT. The SWAT guy talked about softening up bad guys by "hitting them where it won't show," so the good officers wouldn't get into trouble for using excessive force.
Now where can you hit someone where it won't show? On the scalp, so it's covered by hair? I still haven't figured this one out.