We used to get belligerent people in the veterinary medicine library--I know that doesn't sound possible. Usually they were male, non-citizens who wouldn't take No from a woman. There are still cultures where dealing with a woman is an insult. My out was always to give them the name of MY boss, who was male (and in another building) and was paid 4x my salary to handle problem. That seemed to make them happy. A few times we did have to call the police, even though I was probably tougher. A uniform goes a long way.
There are 37,000 words in the contract the customer has with the airlines; and no one has ever read it.
Some people say past behavior should have no bearing. http://www.bizjournals.com/chicago/news/2017/04/11/doctor-pulled-off-united-flight-has-drug-offenses.html