A retired California Highway Patrol officer who had a permit to carry a gun onto a Santee, CA, high school campus is suing the San Diego County Sheriff’s Department for false arrest, excessive force and unlawful search and seizure, among other claims.

The lawsuit, filed Monday in San Diego federal court, asks for at least $20 million in damages, the San Diego Union-Tribune reports.

According to state law, firearms are not allowed on school campuses, although there are several exemptions to the law, one of them pertaining to honorably retired peace officers who are authorized under a permit to carry a concealed or loaded gun.

Robert Pitt, 59, who served in the CHP for 33 years, went to Santana High School the morning of Jan. 21, 2015, with his girlfriend to drop off her daughter. The couple then went to the administrative offices to complain to the vice principal about threats the 15-year-old girl had been receiving from another student, according to the lawsuit.