Many people think that the only real difference is who threw the first punch — but it often isn’t that simple. In fact, throwing the first punch might just be someone’s reaction to a perceived threat — which makes it a defensive gesture instead of an aggressive one.
Self-defense or the defense of others are probably the two most common defenses to the charge of assault and battery. They’re essentially the same defense — the only difference is who is identified as the target of the attack. For example, a man defending himself in a bar fight against another man is exerting his right to self-defense. If he gets into the fight to protect his much smaller friend, then he’s exerting his right to defend someone else against physical harm.
Self-defense is often a carefully scrutinized claim — it isn’t uncommon for there to be witnesses to the confrontation or even video evidence that can help prosecutors and juries decide what was really happening — but no defendant should ever be sure that a jury will see things the same way that he or she does.
In order to prove that an act of violence was really an act of self-defense or the defense of another, the person charged has to establish several things:
Often, it’s also far more important how the fight ended than who threw the first punch. For example, imagine that the defendant reacted to a verbal threat by hitting the so-called victim and knocking him down. Then the defendant quickly fled before the so-called victim could get back up. That’s a very different action — and speaks of a very different motive — than a defendant who continued to beat and kick the man on the ground into unconsciousness, causing severe injury.
Source: FindLaw, “Assault and Battery Defenses,” accessed Sep. 29, 2017