if someone is just trying to rob or jump you on the street, anything goes. Even if the guy after you isn't fighting sh*t dirty, if you get your face broken badly enough, you will be disfigured anyways, don't hold back. He is already not interested in your well being so feel free to return the favor.
i've learned my lesson now, if anyone swings at you for no reason on the street, don't hold back. I bought a $150 hawkbill knife after my little fall and it is coming out and dragged across whatever I can touch next time someone tries to swing at me. After all my BS is taken care of, I will buy a handgun and CWL. Too much hoop jumping in CA or else I would already have one.
if someone wants to call me out, atleast i know first hand how it goes, i was jumped for my car by some punk kid 2 or 3 months ago.
as for jail time or whatever, another thing i learned from my fall, if you are a first time offender for felony assault, you just get a month or two slap on the wrist, no matter how bad the victim is hurt, atleast in CA.
The whole system is bullsh*t and gives perpetrators and criminals lots of play and little recourse besides civil damages for the victim.