TUSCALOOSA, Ala. — In a dramatic show of defiance toward the federal judiciary, Chief Justice Roy S. Moore of the Alabama Supreme Court on Sunday night ordered the state’s probate judges not to issue marriage licenses to gay couples on Monday, the day same-sex marriages were expected to begin here.

“Effective immediately, no probate judge of the State of Alabama nor any agent or employee of any Alabama probate judge shall issue or recognize a marriage license that is inconsistent” with the Alabama Constitution or state law, the chief justice wrote in his order.

The order, coming just hours before the January decisions of United States District Court Judge Callie V. S. Granade were scheduled to take effect, was almost certainly going to thrust this state into legal turmoil. It was not immediately clear how the state’s 68 probate judges, who, like Chief Justice Moore, are popularly elected, would respond to the order.

Since Judge Granade moved last month to declare Alabama’s prohibitions against same-sex marriage unconstitutional, the chief justice has insisted that the probate judges were not required to abide by her decisions. But, in an interview on Wednesday, he said he thought he could do little more than guide the probate judges on how to respond.