Check out the thread entitled, "Need some help here on non office situation" started by Brett on Van Canna's Self Defense Realities. Brett's post has two interesting legal issues:
1. Did he act in self defense in the legal sense in the manner in which he dealt with a perceived or actual threat; and,
2. Can an on-line posting be considered an admission or statement against interest that would be admissible in a criminal or civil action against the writer?
My analyis of the self defense issue is that most prosecutors would probably find the reaction of the initial victim excessive and would be willing to press charges. That is not to say the prosecution would win a trial, but there is a "triable issue."
As to staments on line, those of us who use our real names probably do run the risk of having a statment used against us. If I write, "Some guy looked at my wife funny last night, so I stomped his knee and broke his leg," then I should expect criminal charges. A layer of safety would probably be added to present a situation as hypothetical or having happened to a "friend." It may also be a good idea to change locations that don't alter the vital facts. A rest area in South Carolina could just as easily be a parking lot in Kalamazoo, Michigan.
We think of these on-line threads as an extension of our dojos where a certain level of privacy and protection may be hoped for. However, plenty of people have walked into criminal prosecution due to on-line activity.