United Airlines attracted widespread ridicule Monday after news outlets published videos of airport police violently dragging a passenger from an overbooked flight .

United needed four passengers to give up their seats but was unable to get enough volunteers to take $800 to get off the plane, Audra Bridges, a passenger who posted one video of the incident, told the Louisville Courier-Journal . Airline staff said they would select four passengers at random, but one man refused to leave his seat after he was selected, prompting the airline to call airport police, Bridges said.

United might have been able to avoid all of this by making its passengers aware of the law. Federal regulations require airlines to pay cash lots of it to people they bump from flights against their wishes. (They can also cut a check, which is nearly as good.) If bumping a passenger from a domestic flight delays that passenger by more than two hours, the airline has to pay the passenger 400 percent of the fare to the passengers destination or first stopover, up to a maximum of $1,350. (The infographic at the end of this post explains the few exceptions to this rule.) Heres the relevant section of the Code of Federal Regulations: