Not really: in general, punching somebody in the street is an unlawful act but self-defense makes it justified and thus not punishable (= no conviction and no jail). You definitely can throw punches if it's to defend yourself, others or, in some cases, your property. From what I know, in principle the right to self-defense is somewhat universally recognized. The biggest variable across jurisdictions is the legal reasoning to analyse the situation and determine whether that particular occurrence was self defense or not. And like with all things law, it all depends on the evidence, the lawyers and the judge.
Btw this was not a stab, I find it very interesting to hear opinions from US folks, as - as far as guns are concerned - you guys are confronted with a completely different reality than what I'm used to.