During the prolonged debate over same-sex marriage in America, opponents often warned that if gay marriage were declared a constitutional right, polygamy would be next.

It's become a bit harder to say whether those troubled traditionalists were right — what with a curious, no-decision decision from a federal appeals court in the "Sister Wives" case out of Utah.

And strangely, it may actually be traditionalists — at least, of a certain kind — who should be disappointed that federal judges for now seem skittish about extending America's court-ordered cultural revolution on marriage to plural unions.

Constitutional traditionalists should by rights be eager for liberal jurists to apply the logic of their decisions approving marriage rights for homosexual couples to other, less sympathetic and less influential minorities. That obviously wouldn't resurrect the old-fashioned definition of marriage. But it might help salvage something of the old-fashioned, rule-of-law idea of the Constitution — as a charter of specific rights and definite powers that must be impartially upheld regardless of current fashions and biases.

The case out West was brought by reality TV star Kody Brown and his four co-star wives. Investigated for violating Utah's anti-bigamy law soon after their reality show debuted six years ago, these members of a fundamentalist Mormon sect won a judgment in 2013 from a federal district judge who found the state's marriage restrictions an unconstitutional infringement on their religious and "equal protection" rights.

But two weeks ago the 10th Circuit Court of Appeals overturned that ruling, throwing out the Browns' lawsuit. The appellate judges did not decide that Utah's law passes constitutional muster; they simply refused to consider that question.

Because Utah officials have promised not to enforce the law prohibiting plural marriage unless fraud or abuse is involved, the case is moot, the 10th Circuit said.

The lower court had ridiculed state officials' promise not to prosecute as "a strategic attempt to use the mootness doctrine to evade review" of Utah's marriage law. Of course, that's exactly what it was.

And Harvard law professor and Bloomberg View columnist Noah Feldman is surely right when he calls the appeals court's punt, in its turn, "a sign that the federal courts would like polygamy prosecutions to go away on their own without having to declare a fundamental constitutional right to marry more than one person."

Many advocates of same-sex marriage have long been at pains to deny that arguments for "marriage equality" could ever be used by polygamists. A decade ago, the Star Tribune Editorial Board itself shrugged off suggestions that the same-sex-marriage debate had anything to do with "forcing tolerance of polygamy or other bizarre 'unions' tossed maliciously in the air by the fear mongers … ."

Jonathan Rauch of the Brookings Institution, one of America's most influential advocates for same-sex marriage, has been especially forceful in rejecting the idea that plural marriage deserves the same consideration.

And even the U.S. Supreme Court, in Justice Anthony Kennedy's impassioned opinion in Obergefell vs. Hodges, the 2015 case that declared same-sex marriage to be a constitutional right, kept its distance from polygamy. Kennedy declared, again and again, that it was "marriage between two people" that could not be denied because of gender, because marriage "allows two people to find a life … greater than just the two persons" (emphasis added).

But Chief Justice John Roberts, in his dissent, wasn't buying it. "[M]uch of the majority's reasoning," he wrote, "would apply with equal force to the claim of a fundamental right to plural marriage. If '[t]here is dignity in the bond between two men or two women who seek to marry …,' why would there be any less dignity in the bond between three people … ?"

Why, indeed. It's easy to see why the 10th Circuit Court wasn't in any hurry to take on this challenging question. Having declared that the Constitution guarantees each individual's right to marry whomever he or she loves — never mind society's long-standing rules and norms about what constitutes a proper marriage — the courts may now be hard-pressed to explain why one cannot love and marry a number of people. After all, plural marriage is a tradition with far deeper roots, religious and cultural, than same-sex marriage has.

The only argument that might hold logical water would be a showing that somehow society has a "compelling interest" in withholding recognition and marriage benefits from plural families that it didn't have where same-sex couples were concerned. That could prove a tall order.

Noting all this, Harvard's Feldman came out boldly for a constitutional polygamy right in a column recently reprinted on these pages. "If all humans are inherently entitled to have their marriage choices respected and acknowledged by the government," he wrote, "there's no good reason to exclude … plural marriage."

But here's the irony: While there may not be a "good reason" — meaning a logical constitutional reason — to forbid polygamy while upholding same-sex marriage, society could almost certainly continue to make that choice, and exercise that moral preference, if America had established marriage "equality" nationwide the way Minnesota initially did. That was through an ordinary state law enacted through the political process, not through the courts.

Ordinary laws and policies codify all kinds of social and moral judgments without having to be rigorously consistent or logical about them. And when and if voters change their minds, such laws can swiftly change.

But now that judges have created a sweeping, "fundamental" individual right to define marriage for oneself without regard to society's mores and norms — now the very legitimacy of the courts and the Constitution may be undermined if we don't extend that right, potentially to any number of unconventional unions.

Conservatives may find themselves in an odd position in all this. Conservative judges can of course continue to argue that Obergefell was lousy constitutional law that should be overruled. But barring that, defenders of the rule of law can hardly want to see courts politicize the Constitution still further by using still more tortured logic to deny the rights they have created to less politically influential Americans who may claim them.

D.J. Tice is at Doug.Tice@startribune.com.