A federal appeals court in Ohio upheld on Thursday the right of four states to ban same-sex marriage, contradicting rulings by four similar courts and almost certainly sending the issue on a rapid trajectory to the Supreme Court.

The much-anticipated decision, written by Judge Jeffrey S. Sutton, an appointee of George W. Bush, overturned lower court rulings in Kentucky, Michigan, Ohio and Tennessee that were in favor of same-sex marriage.

“This is the circuit split that will almost surely produce a decision from the Supreme Court, and sooner rather than later,” said Dale Carpenter, a professor of constitutional law at the University of Minnesota. “It’s entirely possible that we could have oral arguments in coming months and a Supreme Court decision by next summer.”

In Thursday’s 2-to-1 decision, by a panel of the United States Court of Appeals for the Sixth Circuit, in Cincinnati, Judge Sutton said that it appears almost inevitable that American law will allow gay couples to marry. But the more fundamental question, he wrote, is: “Who decides?”