Just the other day I was on a Jail RPG, I was a guard. Someone shot a guard and hurt me as well, they then went to an item clearer. I shot them dead. They told me I was free-killing, when it was in my right to kill them once they attacked. He then ran a votekick which only he and his friend participated in and I was banned for several minutes.
Now that is a loving ban outrage. But even I didn't post a topic for it. If you go into a server and act like a douche expect to be banned, there are no global rules, everyone has their own ban threshold.