Legal Question in Personal Injury in California

You haven't asked a question, so there is nothing for us to answer. Your post also isn't clear, since it offers no details about the fight between your friend and the neighbor and does not explain why you think any resulting court case would involve you or your business. You may wish to try again, providing some of the missing details and clarifying what you are trying to ask.

If your friend 'defended himself', meaning an altercation or assault occured, he definitely needs to consult with an experienced criminal defense attorney about the potential for him being arrested, rightly or wrongly, and he may also be involved in civil lawsuit claims, depending upon the actual facts and evidence. So, feel free to have him call. He is not going to get any legitimate or free 'legal advice' from strangers on the internet, only from his own attorney after the attorney learns all the facts. If YOU fear personal involvement in this situation because of your business or personal relationship with your friend, you too need to discuss that with counsel.