Right. A drunken fight isn't worth the trouble. That's a situation where backing down is the right thing... What are you fighting over?
But, sometimes a fight is needed to do the right thing.
Ex. Was at a public camp ground a bunch of years ago on a long weekend, and through the noise of the party at our site I heard a dude yelling at a girl. I grew up in a home where my mom was beaten up about once a month so I'm protective of girls, especially when it comes to domestic violence. I turned my attention to what was going on at this other site, she was crying sitting on a picnic table and he was right in her face yelling... Still not my issue, but then he grabbed her throat, I took off running at the guy, ran him over, ended up on top of the guy and went to town on his face until my friends stopped me.
Sure, I could have walked up, tried to "talk" the guy out of it, but I know how those situations go "f you buddy, this isn't your business", or I could call the cops but by then she's already beaten and he has took off somewhere. Same scenario I saw enough times with my mom.
We ended up sticking with the guy until his friends showed up (guessing they were on a beer run) and they took him home... Surprise, this wasn't the first time he's hit her and they were actually glad someone intervened, and said he had it coming.
Would I have taken an assault charge? Sure, and I would have known I did the best I could.