CINCINNATI (AP) _ Ohio's elections chief is being sued over his investigation into the ballot petitions of a group backing a marijuana legalization effort.

Secretary of State Jon Husted has asked a special investigator to explore why significant numbers of petition signatures collected by ResponsibleOhio were invalid. He's subpoenaed the campaign's director.

A person identified as “John Doe” filed the federal lawsuit Thursday. He wants the court to block the disclosure of his private political speech and his identity to the government.

The suit alleges that the subpoena seeks documents with residents' personal information from ResponsibleOhio, creating a “chilling effect'' and violating the First Amendment and privacy rights of Doe and others who support the legalization proposal. 

ResponsibleOhio, also a defendant in the case, announced the lawsuit.