Giovanni Ramirez is suing the department for defamation, saying Police Chief Charlie Beck showed "reckless disregard for the truth" by calling him the primary aggressor in the March 2011 beating at Dodger Stadium.
Stow, a paramedic from Northern California, was severely beaten, suffered brain damage and is permanently disabled.
Ramirez was never charged in Stow's beating, but was held on a parole violation. Louie Sanchez and Marvin Norwood were later arrested for the crime. They have pleaded not guilty.
The LAPD declined to comment about the lawsuit.
The Associated Press contributed to this report.