Plaintiffs Derek Kitchen and Moudi Sbeity and Kate Call and Karen Archer talk outside the courthouse after a federal appeals court heard oral arguments on a Utah state law forbidding same sex marriage in Denver on April 10. (Rick Wilking/Reuters)

A federal appeals court on Wednesday for the first time employed a landmark Supreme Court decision to declare that the fundamental right to marriage must be extended to gay couples, adding momentum to a remarkably rapid recognition of same-sex marriage by judges nationwide.

The 2-to-1 decision by a panel of the U.S. Court of Appeals for the 10th Circuit upheld a lower court’s decision that Utah’s constitutional amendment prohibiting same-sex marriage could not stand.

The ruling came almost exactly one year after the Supreme Court delivered a pair of major gay rights victories and could be instrumental in returning the issue to the high court for the ultimate decision on whether marriage is a fundamental right that cannot be denied to same-sex couples.

The justices sidestepped that question last June.

But the reasoning used by the majority of Supreme Court justices in rejecting the federal definition of marriage as between one man and one woman has been cited by lower courts in an unbroken string of victories for supporters of gay rights. Judges have struck down state bans from Virginia to Oregon.

This has been accompanied by polls that show an increasing public acceptance of same-sex marriage and, its proponents say, by a growing sense of inevitability.

The 10th Circuit panel, which is based in Denver, became the first appeals court to apply the Supreme Court decision and said it compelled the outcome.

“We hold that the Fourteenth Amendment protects the fundamental right to marry, establish a family, raise children, and enjoy the full protection of a state’s marital laws,” Circuit Judge Carlos F. Lucero wrote. “A state may not deny the issuance of a marriage license to two persons, or refuse to recognize their marriage, based solely upon the sex of the persons in the marriage union.”

Lucero, whom President Bill Clinton nominated to the bench, was joined in the decision by Circuit Judge Jerome A. Holmes, a George W. Bush nominee.

Circuit Judge Paul J. Kelly Jr., who was nominated by President George H.W. Bush, dissented. That makes him the only federal judge since the Supreme Court’s decision in U.S. v. Windsor last year to say he would leave a state ban in place.

Kelly said that marriage between people of the same gender is not a fundamental right and that the decision whether to open the institution to gay couples “belongs to the electorate and their representatives.”

He said judges “should resist the temptation to become philosopher-kings, imposing our views under the guise of constitutional interpretation of the 14th Amendment.”

Lucero said it might be “preferable” to let the national debate play out “through legislative and democratic channels.” But he added that “the protection and exercise of fundamental rights are not matters for opinion polls or the ballot box.”

There is irony in the fact that Utah, one of the most conservative states, is at the forefront of returning the issue to the Supreme Court. After a federal judge in Salt Lake City overturned the state’s ban late last year, more than 1,000 couples were wed before the high court stayed his decision. That stay will remain in place while the state considers its next step, the appellate panel said.

Utah Attorney General Sean D. Reyes (R) said in a statement that he had not decided whether to ask the full 10th Circuit appeals court to review the panel’s decision but that the ultimate question must be decided by the Supreme Court.

Although Utah lost, he said, “we are pleased that the ruling has been issued and takes us one step closer to reaching certainty and finality for all Utahns on such an important issue.”

Rulings from the 10th Circuit are binding in Colorado, Kansas, New Mexico, Oklahoma, Utah and Wyoming. Of the six, only New Mexico currently allows same-sex marriage.

Because the panel stayed its order, the bans in the other states are not affected. The same panel of judges has heard an appeal of a lower court’s ruling that Oklahoma’s ban is unconstitutional but it has not ruled in that case.

The issue of same-sex marriage is working its way through appeals courts nationwide. The U.S. Court of Appeals for the 4th Circuit, based in Richmond, Va., for instance, is reviewing a decision that struck down Virginia’s ban. In August, the U.S. Court of Appeals for the 6th Circuit, based in Cincinnati, will hear arguments in cases involving all four states in its jurisdiction, where bans have been struck down or states have been ordered to recognize same-sex marriages performed elsewhere.

The Supreme Court is most likely to take up the issue if various appellate courts disagree about whether the bans are unconstitutional. But most observers say the Supreme Court will need to decide the issue at some point, even if the lower courts are all in agreement.

In Wednesday’s decision, Lucero rejected all of Utah’s arguments that it had legitimate reasons to limit marriage to a man and a woman. He said that limiting marriage to couples that could naturally procreate was not valid, because elderly and infertile heterosexual couples are allowed to marry, as well as those who do not intend to have children.

He said the panel joined other courts who found it “wholly illogical to believe that state recognition of the love and commitment between same-sex couples will alter the most intimate and personal decisions of opposite-sex couples.”

And he rejected “slippery-slope” arguments that recognizing same-sex marriage would necessarily require the recognition of other relationships. “Unlike polygamous or incestuous marriages, the Supreme Court has explicitly extended constitutional protection to intimate same-sex relationships,” Lucero said.

Kate Kendell, executive director of the National Center for Lesbian Rights, said the appeals court opinion “marks an indelible milestone in our nation’s journey to full inclusion — and one that will undoubtedly influence other courts in the months to come.”

Opponents were disappointed.

“While judges can, by judicial fiat, declare same-sex ‘marriage’ legal, they will never be able to make it right,” said Tony Perkins, president of the Family Research Council. “The courts, for all their power, can’t overturn natural law.”

In a statement on its Web site, the Church of Jesus Christ of Latter-day Saints, based in Utah, said it continues to believe that “marriage should be between a man and a woman but that “all people should be treated with respect.” Anticipating that the final decision will be the Supreme Court’s, the church said, “It is our hope that the nation’s highest court will uphold traditional marriage.”

At the same time that the court in Denver was acting, a federal district judge on Wednesday struck down Indiana’s ban on same-sex marriage and allowed gay couples in that state to wed immediately.