Good luck, buddy. The airline staff asked you to leave the aircraft. You refused, even though the law says you leave when asked. The police dragged your ass off the plane. You should be in jail right now, not preparing a frivolous lawsuit.
Good try DonW. If they asked you to jump off the bridge would you jump? The man was within his right to stay in the seat according to United’s rules of carriage on their website. It was an illegal order to forcibly volunteer. He was under no obligation and the “cops” had no right to remove him. They are all now suspended.