what gives them the right to put my life in great danger, and two, why don't they have to inform me they did this.
First of all, rather obviously, someone did inform you of this. Second, I have no idea who "they" are. Third, if the prosecutor or defense attorney in a criminal matter thinks someone is a witness, then he/she will put that person's name on a witness list (assuming that's what "on paper as a witness" means). No one needs to notify you of this. Why don't they need to notify you? Because there's no law that says they do.
Most of the rest of your post makes little sense, but if you're associating with people who will inflict violence on you solely because your name appears on a witness list, that's your problem and yours alone. Maybe you ought not to associate with such low-life criminals.
putting someone's name as a witness on paper can jeopardize their life, not just in the biker community, but in society in general.
Ummm...no. Not "in society in general." When was the last time you heard about someone being attacked
solely because his/her name appeared on a witness list in connection with a criminal matter?
By the way, how would anyone know that your name is on a witness list? Let me submit to you that posting on a legal message board about an active criminal case, apparently using your real name as your screen name, is probably far more damaging than anything else. If, in fact, your screen name is your real name, you ought to give serious consideration to changing it.
A young man almost ran over my daughter on a motorcycle. My son found and assaulted him. I was on a club run across the state. Knew nothing until I returned home. The next day he turned himself in. Not having relevant information of the incident cause out of town, why am I on their witness list.
Why don't you call the person who prepared this witness list or your son's lawyer and ask? All anyone here can tell you that, just because you didn't personally witness your son's alleged crime doesn't mean you don't have relevant information. In fact, that you referred to an evidentiary privilege (albeit one that doesn't exist) suggests you already know why you might be on the list. You told us that you heard about the incident when you returned home. Since you haven't told us anything to the contrary, it's entirely likely that your son told you about the incident, and what he told you could be valuable evidence.
It appears to me this could easily be used negatively against anyone.
Sure. In theory, it could. But most folks don't behave that way.