If someone agrees to fight with you and they get their ass handed to them, how much of a liability is your MMA training as it relates to legal problems? What is the likely outcome if their was an obvious skill difference?
Why would you agree to fight someone? Because they want to see if they can take you? Do you owe them a shot at the title?
The law says you can use that amount of force necessary to defend yourself. If you go beyond that and unnecessarily injure or cripple someone, you can be charged with a crime.
Most states even have laws that prohibit fighting as a form of disorderly conduct or afray even if neither combatant wishes to prefer charges.
The odds are against you. Keep it on the mat or in the ring....or roll the dice and take your chances.
All they have to do is say they never agreed and you're toast if you pound em.