shorasOverbooking flights is a common thing, but doesn't often lead to issues like that. If it does, there should be a different way to solve it.
They do solve it a different way, priority is given to the people already in the plane and preventing overbooking is done at the gate. There is a strong policy that's put in place for that and they actually are allowed to deny boarding for. If it happens any other way, some rule or law somewhere is probably being broken.
What United did by trying to get some of their employees on a full flight, legally speaking, has nothing to do with overbooking. Overbooking is defined in terms of oversales, which means the employees they were trying to put on were not involved with overbooking. They are not allowed to kick you off for this, both in terms of the law and in United's contract (and they wouldn't be allowed to kick you off even if it were a matter of overbooking).
VouriThe captain is in charge of the aircraft. And if he or she decides that someone needs to be offloaded, that command has to be obeyed. From the moment that the unfortunate individual in this case said, "I'm staying put", he became a disruptive passenger.
From that moment he was disobeying the captain's command. Officials were legally entitled to remove him, and as the videos show, he was dragged from the plane. It appears from the evidence that the law was broken - by him, not by the airline. But I would be surprised if United pressed charges.
You are allowed to remove someone that is already disruptive (specifically, within United's contract, "disorderly, offensive, abusive, or violent"). You are not allowed to attempt to remove someone, have them become "disruptive" by refusing (as is their right, since attempting to remove them was illegal in the first place), and then use that as justification for removing them. United's contract had nothing about removing people already on a plane to put others on it, they had no grounds to attempt to remove him in the first place.
e: sorta ninja'd, didn't realize how long it took me to write this :B