Bucking the pro-gay-marriage rulings of four other U.S. circuit courts and setting up an inevitable final showdown at the U.S. Supreme Court as soon as 2015 on the matter, the 6th Circuit Court of Appeals on Thursday upheld bans on same-sex marriage in Michigan, Ohio, Pennsylvania and Kentucky.

The decision was the first ray of light for anti-gay-marriage forces in over a year, since the Supreme Court ruled in United States v. Windsor in June 2013 that the Defense of Marriage Act violated gays’ and lesbians’ constitutional rights to due process and equal protection under the law. Same-sex marriage advocates immediately vowed to appeal.

Since Windsor, dozens of federal district court and appellate judges have interpreted the ruling to mean that it is unconstitutional for states to deny same-sex couples the same right to wed afforded to heterosexual couples. As a result, the number of states that recognize same-sex marriage has risen from 12 (plus the District of Columbia) to, at last count, 32. As of Wednesday, it is also legal in the city and county of St. Louis but not the rest of Missouri.

Similarly, district courts in the four states under the 6th Circuit’s jurisdiction have ruled in favor of striking down marriage bans and requiring those states to recognize same-sex marriages performed in other states. Those rulings invalidated referendums in all four states that amended their state constitutions to bar recognition of same-sex marriage. More than 300 same-sex couples married in Michigan earlier this year before the 6th Circuit stayed the district court decision. The status of those couples’ marriages remains unclear. Thursday’s decision did not address that question.

The 6th Circuit’s Judge Jeffrey Sutton, writing for the majority (in a 2-1 vote, with Judge Deborah Cook), took a dramatically different path from his colleagues in other circuits, insisting that gay marriage remains a strikingly new concept for American society and, as such, it deserves more debate and discussion by the public. To short-circuit that process, which he says has already borne significant success for same-sex marriage advocates, would risk alienating potential gay-rights supporters who want to decide the issue rather than have courts do so.

“When the courts do not let the people resolve new social issues like this one, they perpetuate the idea that the heroes in these change events are judges and lawyers,” wrote Sutton, an appointee of President George W. Bush and a former law clerk for Supreme Court Justice Antonin Scalia. “Better in this instance, we think, to allow change through the customary political processes, in which the people, gay and straight alike, become the heroes of their own stories by meeting each other not as adversaries in a court system but as fellow citizens seeking to resolve a new social issue in a fair-minded way.”

Sutton’s decision was consistent with his questioning of attorneys seeking to strike down same-sex marriage bans during a three-hour session in Cincinnati on Aug. 6, when the panel considered six similar cases from the four states under its jurisdiction. “Don’t you think,” Sutton asked the attorney fighting Michigan’s gay marriage ban, “you’re more likely to change hearts and minds by using the democratic process?”

Those attorneys rejected that notion, insisting that subjecting a minority’s rights to a plebiscite would have allowed segregation and bans on mixed-race marriages to persist perhaps even to the present day. That was the theme sounded by 6th Circuit Judge Martha Craig Daughtrey in her stinging dissent. She mocked Sutton for writing an opinion that “would make an engrossing TED talk or, possibly, an introductory lecture in political philosophy” but “wholly fails to grapple with the relevant constitutional question” before the court. She lambasted him for treating “both the issues and the litigants as mere abstractions” rather than real people for whom the denial of marriage rights imperils their legal status as spouses and parents to their children.

“This makes it very likely that the U.S. Supreme Court will accept an appeal of that ruling and resolve the matter of same-sex marriage nationally because now there is a split among the federal circuit courts on the question of whether same-sex marriage bans are unconstitutional,” wrote veteran gay journalist Rex Wockner on his blog late Thursday. “The Supreme Court’s ultimate determination would either legalize same-sex marriage in the final 18 states or possibly undo the legalization of same-sex marriage in the 32 states that now have it, a less likely possibility as most observers see it.”

The ruling heartened foes of same-sex marriage, who insisted that lower court judges misinterpreted the Windsor decision. “The people of every state should remain free to affirm marriage as the union of a man and a woman in their laws,” wrote Byron Babione, senior counsel for the Alliance Defending Freedom, which submitted friend-of-the-court briefs in three of the cases arguing against a judicial fiat in favor of same-sex marriage. “As the 6th Circuit rightly concluded, the Constitution does not demand that one irreversible view of marriage be judicially imposed on everyone. The 6th Circuit’s decision is consistent with the U.S. Supreme Court’s acknowledgment in Windsor that marriage law is the business of the states.”

Reaction was swift and stern from gay-marriage advocates. ACLU staff attorney Chase Strangio, whose ACLU Lesbian, Gay, Bisexual and Transgender Project represented Ohio plaintiffs John Arthur and James Obergefell in one of the cases before the 6th Circuit, called the decision “an outlier that’s incompatible with the 50 other rulings that uphold fairness for all families, as well as with the Supreme Court's decision to let marriage equality rulings stand in Indiana, Wisconsin, Utah, Oklahoma and Virginia.” (In October the Supreme Court declined to take up any appeals of pro-gay-marriage rulings in the circuits that decided for same-sex couples, effectively legalizing it in every state in those circuits.)

Arthur and Obergefell, together for more than two decades, flew from Ohio to Maryland to marry in July 2013. Two months later, Arthur succumbed to amyotrophic lateral sclerosis. Before his death, they sued Ohio to have his death certificate list him as married and Obergefell as his surviving spouse. “We will be filing for Supreme Court review right away and hope that through this deeply disappointing ruling, we will be able to bring a uniform rule of equality to the entire country,” Strangio said in a statement.

While Sutton argued that allowing the democratic process to take its course would produce the best, albeit slower, results for gay couples, his ruling could have the opposite result. The Supreme Court chose not to rule nationally on the matter earlier this fall in part because there was no inconsistency among appellate court decisions. Now that there is one, the high court may take up the matter and make a sweeping national ruling far sooner, advocates say.

“The one small upside is that, as Justice Ruth Bader Ginsburg indicated, if there’s a split, the Supreme Court’s hand would be forced,” said Gina Calcagno, coalition director for Michigan for Marriage, an advocacy group pushing for legal same-sex marriage in the Wolverine State. “That is a bit of cold comfort for us. We’re still disappointed in this decision, but it means we may have national resolution far more quickly.”