A 46-year-old Stamford resident, arrested after holding a sign on a sidewalk reading “Cops Ahead” while officers were stopping motorists for cellphone violations, has filed a First Amendment lawsuit against the arresting police sergeant.

In his federal lawsuit, filed Monday in U.S. District Court for the District of Connecticut in Bridgeport, Michael Friend said Stamford Sgt. Richard Gasparino had no right to take away his cellphone or arrest him. He claimed that in doing so, the officer violated his First and Fourth Amendment rights against warrantless seizures.