The Southern Poverty Law Center has filed a supplement to its ongoing ethics complaint against Alabama Chief Justice Roy Moore.

In Wednesday's filing, the group called for Moore's removal from the bench for advising probate judges in the state to enforce Alabama's ban on gay marriage.

(Related: Alabama Chief Justice Roy Moore calls on judges to enforce state's gay marriage ban.)

“Chief Justice Roy Moore is once again demonstrating that he is unfit to hold office,” SPLC President Richard Cohen said. “Despite the fact that Alabama probate judges are under a federal court order that bars them from discriminating against same-sex couples seeking marriage licenses, Justice Moore has irresponsibly advised them to do the opposite.”

The Judicial Inquiry Commission removed Moore from the office of chief justice 13 years ago for refusing to comply with a federal court order to remove a Ten Commandments monument he installed from the state judicial building.

“You would think after being removed from the bench once before that the chief justice would know better,” Cohen said.

The controversy, however, turned Moore into a Christian celebrity. Voters returned Moore to the office of chief justice in 2012.

“Just as Chief Justice Moore's previous refusal to comply with a federal court order disqualified him for judicial office and necessitated his removal from the bench, his advising other judges to violate a federal court order also requires his removal as Chief Justice of this state's highest court,” the group stated in its supplemental filing.

(Related: Hillary Clinton criticizes Roy Moore's “unconstitutional” order to block gay marriage.)