The one thing that puts United fully at fault here:
United said:
Flight 3411 from Chicago to Louisville was overbooked. After our team looked for volunteers, one customer refused to leave the aircraft voluntarily and law enforcement was asked to come to the gate.
Now, the definition of
volunteer is to undertake or offer a decision based on one's own free will. If someone doesn't do something voluntarily, then forcing them to do it when they refuse means that it
wasn't voluntary in the first place. That wording right there is enough of a case for Dr. Dau to sue the pants off United. Also, wiping $500,000,000 from their stocks might get them to reconsider the unnecessary use of force and overbooking, which is a practice purely for profitable means. I bet having a practice of leaving at least 4 seats unallocated until United confirms no extra staff needs to be onboard would not cost them $500,000,000 (plus all the negative PR shooing people to take alternative airlines) in lost revenue.
Also, had a quick look at United's conditions of carriage:
RULE 25 DENIED BOARDING COMPENSATION said:
If there are not enough volunteers, other Passengers may be denied boarding involuntarily in accordance with UA?s boarding priority
They say 'denied boarding'. In this case, the passenger had
already boarded, meaning that they had no grounds for forcible removal. There's stuff about removal of passengers (Rule 21 [https://www.united.com/web/en-US/content/contract-of-carriage.aspx#sec21]) but none of those caveats would apply to Dr. Dau.
United dropped the ball on this one, big time. Violence against a law-abiding paying customer who followed all the rules and has every right to refuse the act of volunteering is completely unwarranted, no matter how much of an asshole he allegedly was (one first-hand witness didn't think this was the case [http://www.chicagotribune.com/news/opinion/letters/ct-united-flight-3411-man-dragged-witness-20170411-story.html], and it was the ticket agent who was being rude. As an eyewitness, I believe them over any journalistic reports). I think most people here feel the same way. I'm not anti-authoritarian, for the most part, but this reeks of insidious brutality from an authority figure overstepping their bounds, which is an all-too common criticism of authority in the United States in general.