I'm seeing in some places that he might not have any room to sue United due to language within their Contract of Carriage, but I'm not a legal expert in that regard. If anything, it's more likely the Chicago Department of Aviation will be found liable for excessive force in the removal of the passenger from the plane. The city of Chicago already has a hefty fund to pay out victims of police misconduct, but I'm not sure if that only applies to victims of Chicago PD or if it would also apply to Chicago Department of Aviation law enforcement. I probably still will just because I live near O'Hare, and United is the only carrier that flies directly to the area where I grew up. Southwest does as well, but it takes 30-45 minutes in no traffic to get to Midway whereas O'Hare takes me 10 minutes in no traffic. Plus I'm not a fan of Southwest's seating system, but that's a matter of personal preference.