I'm a police officer. I've made tons of arrests and written countless reports. I don't get a kick out of arresting people. Someone has to truly deserve to go to jail before those metal bracelets go on.
I also train in Krav Maga for my own self defense.
The scenario above in the theater.....tough call for the scene officer. It's a good thing he left the theater. As a man, as a husband and father, I can totally sympathize with wanting to beat the shit out of some ass who insults your wife and came forward towards you with his two buddies behind him. Sucks because given all the facts, if the husband is still on the scene, he's probably getting a ride to jail. Id prob be so conflicted, Id make my Sgt tell me to make the arrest. I'd truly be that conflicted. Law is the law though. It's a different world than a couple of decades ago. It's a very sensitive world and super litigious.
It's all about who was the aggressor, what do unbiased witnesses say, injuries to both parties, the versions the two parties give. Lots of facts to take in. If the husband can say that he was in physical fear for himself and wife because there were three of them and one had already pushed his wife several times as well as verbally insulted her well that's different. But he wasn't backed into a corner, he could have left. Words won't usually wind you up in jail unless they are threats though.
So jerk bumps his wife twice and then makes his comment, husband could have left theater and called for a patrol car and taken a report right there. No arrest would have been made because it was a misdemeanor offense not occurring in the officers presence. But an arrest warrant could be issued after a detective reviewed the report and spoke to the victim.
Jerks are bothering you and yours, alert the movie staff. Get a refund. F those jerks. WAY easier said than done though. You don't want to appear weak. You want to stand up for your wife. I get it.
You have so much to lose putting your hands on some idiot. You could lose your freedom, job, tons of money, spending time dealing with probation officers, you name it.
Days of duels and men settling issues out back and once the fight is over, it's over is well....over. Even if you were right, no question beating his ass after he swung first, he could still try and sue you for civil/medical damages and maybe win. Just be careful. Be smart.
I would try and do my best writing to arrest the jerk for simple assaulting the wife before getting knocked the F out. If the husband had to go, I'd make the jerk go too. Maybe he'd beat the charge but he wouldn't beat that ride.