I look at it like this; the law is secondary to my well being. Survive first. If you survive then you can worry about consequence. If you dont survive, none of it matters.
You can tell when you have an aggressive opponent. Observation is a huge part of self defense. If you find yourself in a bad situation your awareness has already failed you. Dont let it fail you again because of fear from repercussion. Use it to read your opponents body language and you will know if he plans to attack. Hit them first, fast, and hard and get out quickly. Would I recommend trying to grab and control straight off the bat? No. After a strike or feint, sure.
"When I let Go of who I am, I become who I might be." Lao Tzu