One of the most remarked-upon aspects of the first round of Prop 8 litigation, that concluded this week with a 2-1 defeat for the initiative at the 9th Circuit Court of Appeals, was the weakness of the case against gay marriage. As Andrew Cohen explained at the time, at every turn Judge Vaughn Walker, who presided over the trial, expressed frustration at the fact that the opponents of gay marriage either had no case or couldn’t be bothered to make one. Arguing for the gay marriage ban, seasoned attorney Charles Cooper called only two witnesses (the plaintiffs called 17), one of whom was not deemed qualified to testify as an expert. As Cooper finally explained in his closing argument, “Your honor, you don’t have to have evidence for this. … You only need to go back to your chambers and pull down any dictionary or book that defines marriage,” Cooper told the judge. “You won’t find it had anything to do with homosexuality.”

This defense satisfied almost no one. Ted Olson, the plaintiff’s attorney, was absolutely flummoxed by Cooper’s claim that he had no burden to do anything beside assert the immutability of traditional marriage. In his closing argument, a perplexed Olson replied, “You can’t take away the rights of tens of thousands of persons and come in here and say ‘I don’t know’ and ‘I don’t have to prove anything.’ ” An equally maddened Judge Walker agreed, railing in his opinion about how the Prop 8 proponents had failed to produce promised evidence and testimony. Even conservative groups wrung their hands, questioning whether Prop 8 had been “adequately defended” at the hearing. Then again, perhaps punting on Prop 8 was a strategic decision. Doing so allowed the supporters of Prop 8 to argue that the fix was in. Judge Walker, who is gay, and the Hollywood appeals court would never have given them a fair shake in the first place.

Or, perhaps, there was another explanation. Perhaps, as many speculated at the time, it reflected the deeper reality that there was no factual or empirical case to be made: The evidence, the data, and the experts overwhelming agree that gay marriage does not harm children. And that leaves opponents of gay marriage to argue a tautology: Gay marriage is wrong because it’s wrong.

One thing is certain: The problem for proponents of Prop 8 wasn’t that they hadn’t had enough time to hone their argument. Four months later, during the argument at the appeals court, Charles Cooper again found himself unable to articulate a single plausible reason for why the ban existed in California. A far more empathetic judge in Randy Smith tried to coax one from Cooper: “But what is the rational basis for [the] initiative when California law says homosexual couples have all the rights of marriage, all the rights of child rearing, all the rights that others have?” asked Smith. “What is the rational basis then [for Proposition 8] if in fact the homosexual couples have all the rights that heterosexual couples have? We’re left with a word: marriage. What is the rational basis for that?”

At the podium, Cooper’s answer was more or less a Zen koan: “Your honor, you’re left with a word, but a word that essentially is the institution,” said Cooper. “If you redefine the word, you change the institution. You cannot separate the two.” It was either the sound of one hand clapping or the perfect response to a question that appears to have no good answer.

It was, in any event, enough for Judge Smith. Unable to get a satisfactory answer from Cooper, Smith tried valiantly to muster one for himself in a lengthy dissenting opinion. What he produced was slightly less oddly metaphysical than Cooper’s statements at trial, but not much more filling. (Lest you think this is a partisan charge, here’s Maggie Gallagher making the same observation at the National Review Online about a timid dissent that amounts to nothing more than “don’t go after me!”)

Judge Smith’s argument begins with a lengthy discussion of a 1971 case denying a marriage license to a gay couple from the Minnesota Supreme Court called Baker v. Nelson, which the U.S. Supreme Court summarily dismissed in 1972 “for want of a substantial federal question.” Because it came up to the high court through mandatory appellate review, it stands as a precedent for what Judge Smith describes as a preference that courts exercise “restraint” when it comes to addressing due process and equal protection challenges against laws prohibiting same-sex marriage. Judge Smith is angry that the majority blew off Baker in a footnote. (In that footnote, the majority suggests that Baker raises different questions and is less relevant than subsequent cases, including Romer v Evans.) As Western State University College of Law professor David Groshoff argues, “Baker’s relevance in this debate more or less disappeared in Minnesota in 2001, and several years later nationwide, when sodomy laws no longer applied to consenting adults.” In other words, Judge Smith is grasping.

He’s only getting started, however. Smith goes on to explain that under a rational-basis review, the government can create classifications and need not “actually articulate at any time the purpose or rationale supporting its classification.” Indeed, he argues the courts must support these classifications so long as there is “any reasonably conceivable state of facts that could provide a rational basis for the classification.” To make matters even easier on the government, Smith adds that it need not produce evidence that the classification is rational, and “may be based on rational speculation or empirical data.”

Smith’s reasoning does an incredible thing: It produces a justification for why the proponents of a gay marriage ban need offer no justification. Where Cooper could only deliver a “because-I-say-so” theory of jurisprudence, Smith attempts to come to the rescue with a “because-someone-says-so” theory of his own.

Perhaps sensing that he may require a higher power as well, Smith then turns to Justice Antonin Scalia—specifically his argument in the dissenting opinion in Lawrence v. Texas that states can use their police powers to regulate “morals.” Of course, Smith must acknowledge that Scalia’s argument isn’t the law—it was, after all, the dissenting opinion.

Nonetheless, Smith concludes that there are rational reasons to ban gay marriage in California. These reasons are, as he spells them out, “a responsible procreation theory” and “an optimal parenting theory.” Judge Smith concludes that Prop 8 “preserves the fundamental and historical purposes of marriage” and notes that the proponents of Prop 8 “offer many judicial opinions and secondary authorities” supporting both the responsible procreation theory and the optimal parenting theory. He could tell you about them but, well, why drag fact into the case at this juncture? Having lowered the bar so far already, it doesn’t matter if these theories are persuasive or not. All you need to know is that they exist. As Smith lays it out, since both sides “offer evidence” and the question of optimal parenting is still “debatable”—and will remain debatable as long as no fact or evidence is required to prevail in the debate—the tie goes to the state. Gay marriage can be banned.

So there you have it: That’s the best case that can be made against gay marriage. An appeals court dissent that rests on the premise that states needn’t act rationally, or offer evidence of rationality, or even be rational in creating classifications, so long as someone publishes a study and someone else believes it. That’s the best they’ve got, it seems.

That is not legal argument or empirical evidence. It is the death rattle of a movement that has no legal argument or empirical evidence. Nobody disputes the fact that Americans opposed to gay marriage believe passionately in their ideas and arguments. But that doesn’t necessarily mean those arguments should win in a court. The best thing that could have happened in the Prop 8 case just happened. The dissent has no clothes.