A New York man is suing the Department of Homeland Security, alleging federal agents violated his First Amendment rights by tracking him down and warning him over an email criticizing the former head of Immigration and Customs Enforcement.

David Streever of Rochester, New York, filed the lawsuit Monday in federal court in Washington, D.C., with the nonprofit organization Foundation for Individual Rights and Expression. The complaint argued that the DHS launched an investigation and intimidated him over constitutionally protected political speech.