Again, an understanding of the law in your situation would better help. You stated that you could have hit him without warning because you were in fear. Depends on the state. In some states you have the "duty to retreat" so why not just get back into your car? When you go to court you can bet that the attorney's are going to turn that around on you that you WANTED the confrontation and that you were trained (civil liability is only tipping the scales in your favor) and took advantage of their client to hurt him.
All I have is a bachelor's myself & I just got it for promotion points in the Army, then I started applying with my fireteam & I got hooked. As for the duty to retreat laws; there isn't any in WV. We adapted a castle law which allows me to use whatever force I feel is justified if I am threated or assault, including lethal force. The only restriction is I can't be doing anything illegal at the time of the event for it to protected under the castle law...
A brawl in the bar parking lot isn't covered under the fact I'd be guilty of public intox, but by the same standard I have no duty to retreat in public. So if I'm attacked, for any reason I don't have to retreat more so a good lawyer can disprove the "duty to retreat" in public claim, since you have no where to retreat to. So in the hypothetical extention of the same situation; I'm sure I can make the arguement that with a person 100lbs heavier then me is a significant threat the my safety & having threaten my life left no where to retreat to; retreating to my car only leaves me "pinned" and unable to properly defend myself. The legal arguement is sound & just leaves me to convense a jury; which is why I don't bother with legal stuff because until your in a trial; legal defenses don't matter.
If you don't feel comfortable with the legal aspect then bring in an attorney like alot of instructors do to explain the law and go over situations like that and what you can do. Also, explain that you have to do what you have to do sometimes and can't worry about "legal duty" in those situations. In today's society, a fight isn't over when the physical confrontation ends, it ends when it is finally over and there is no criminal charges or civil suits. If you are professing to teach "self-defense" then you need to teach everything that encompasses or just say you teach "fighting" or you teach "conflict resolution".
Unfortunately it is my personal experience that laws on the books don't matter, its the LEO's and Judge's interpetation of the law that counts. The LEO arrests you based their interpetiation of what they assume happened or is happening and the judge convicts you on what they assume occurred. Juries don't matter a great deal since the judge is responsible for administering jury instructions and a well doctumented case of where judges give misleading instructions based on laws. Now I am not saying all judges do this; but it is a well documented fact that many do...
If the local BJJ instructor who is also a local LEO teachs anything about the law to his students he is in violation of a specific WV code, which is a felony as only the first count, counts as a misdemeaner. I will tell people where to look up the codes themselves & I will advise them to see a lawyer. I can't afford to have a lawyer to come in to give a class & it simply is not my legal or moral responsibility to do so.
To take it even further, the legal system is broken when it comes to self-defense laws and in many cases staying alive means breaking the law. I've seen allot of SD guys teach according to what their local law where and handicap students (seen a lot of freezing here) because thay are given conflicting information; SD-wise you need to do "A", but legally you need to do "Z" and it causes the conflict that leads to freezing. Not one of my students have frozen or hesitated yet, because I don't give them conflicting information. I tell them using some techniques can send them to jail if they use them, but I also tell they have a choise a) take a chance on going to jail and b) take a chance on being crippled, maimed or killed.
Its a simple matter of priorities;
1. Immidiate Need: Staying alive...
2. Urgent Need: Staying unharmed...
3. Required Need: Food, Water, Shelter, Security & Medic needs
4. Social Need: Staying out of Jail/Legal Trouble, Paying Bills or Picking up Flowers for sposes birthday...
Staying alive can range from handing over your wallet to a mugger to letting go of your ego or to taking an attacker's life. In order to go to jail you need to stay alive to do that. I have no illusions about the law; its
a construct of a human mind with human goals & to be honest raises a society of cattle. You aren't concerned withpaying your bills while having to defend yourself or get flowers for your wife. So why hamper yourself, with worrying about legal issues; even if you obey the law and fullfill your "duty to retreat" you can still be charged. So trying to worry about something which won't matter until later on; because you have to have a bond hearing, intial apprearance, grand jury indictment before you even see trial. Legal defense don't matter until trial and have no effect on the LEO's investigation.