An air marshal who said his free speech rights were restricted can proceed with his lawsuit against Homeland Security chief Michael Chertoff and others, a federal judge has ruled.

The government had sought to dismiss the lawsuit, filed in April by the American Civil Liberties Union of Southern California on behalf of Frank Terreri.

But in a ruling released Wednesday, U.S. District Judge Edward Rafeedie sided with the air marshal and allowed the lawsuit to move forward.

An attempt to reach an air marshal spokesman was unsuccessful late Wednesday.

Terreri, 38, was removed from flight duty and placed under investigation in October 2004 after complaining to a colleague about a magazine story discussing operational details of the air marshal program, according to ACLU of Southern California attorney Peter Eliasberg.

Rules imposed on air marshals in August 2002 prohibited airline security agents from criticizing other Federal Air Marshal Service employees, speaking publicly and releasing information about the division, the lawsuit said.

In July, the government changed its policy, but Eliasberg said it still restricted employees' right to free expression. Terreri amended his lawsuit in August to challenge the constitutionality of the new policy, the attorney said.

Terreri was returned to active flight duty the day after filing the lawsuit, Eliasberg said.