Security guard decks a man and knocks him out cold, who's at fault

A security guard at the Bone Yard on Station Street in Chattanooga, TN., punched a man he claims was drunk. Caleb Young was pushed around and once he was punched hit the ground and lay there for approximately 2 minutes before bystanders stopped to check on him. He has filed a lawsuit. He lost teeth, had jaw damage, and his head was bleeding.