Alabama Chief Justice Roy Moore on Wednesday issued an administrative order calling on judges to stop issuing marriage licenses to gay and lesbian couples.

Moore, an outspoken opponent of marriage equality, said that probate judges, who in Alabama issue such licenses, have a “ministerial duty” to comply with a voter-approved constitutional amendment and a state law that define marriage as a heterosexual union.

“Until further order by the Alabama Supreme Court, the existing orders of the Alabama Supreme Court that Alabama probate judges have a ministerial duty not to issue any marriage license contrary to the Alabama Sanctity of Marriage Amendment or the Alabama Marriage Protection Act remain in full force and effect,” he wrote.

The probate court in Mobile County, among the busiest in the state, quickly responded, saying on its website that it was “not issuing marriage licenses to any applicants until further notice.”

That probate office was involved in litigation last year which resulted in a federal judge issuing an injunction ordering probate judges in the state to issue marriage licenses to gay couples.

Moore's move comes roughly six months after the Supreme Court in Obergefell v. Hodges ruled that gay couples have a constitutional right to marry.

Ronald Krotoszynski, a law professor at the University of Alabama, told The New York Times that Moore's order “constitutes an exercise in futility.”

“At best, it sows chaos and confusion, at worst, it forces couples to bring federal court litigation in order to exercise a clearly established federal constitutional right,” he wrote in an email.