People will self police when there is a “do not cross this line” policy in place. It forces a “when in doubt, dont do it” mentality.
Worked in a bar in my younger college years with such a policy and they had a reputation for no BS. One fight in the couple of years I was there…it was broken up by other patrons and the two fighters were banned. I dropped in many years later, the place still feels the same, alot of friendly faces and the names of those two guys were still in the spiral notebook. There were only a handful of names listed after theirs. Amazingly, having a standard of behavior works.
Are the banned patrons evil? No but they decided the rules didnt apply….they were wrong. Things escalate without lines in the sand. Ive been guilty of raising my rhetoric on occasion with some who appear to be cultivating a personal confrontation. I would not have if there were enforced standards.