At Tuesday’s oral argument before the Seventh Circuit, Judge Richard Posner shredded two states’ defenses of their laws excluding gay couples from marriage. (You can listen to the Indiana argument here.  The Wisconsin argument, which immediately followed, is available here.) Along with the two other judges on the panel, Ann Claire Williams and David Hamilton, he seems poised to strike down the marriage limitations on Equal Protection grounds. But Posner was the most tenacious and trenchant in his questioning of the states’ lawyers, and was frequently amused by what he was hearing from the states. Overnight, he’s become a hero of the gay-marriage movement (see here, herehere, and here).

In Baskin v. Bogan, Indiana argued that marriage was designed to deal with the problem of unintended pregnancies. The state asserted a need to “nudge” couples to stay together to raise such children and offered that it does so by recognizing a special status for their relationship called marriage, with accompanying rights under the law.

Call it the “heterosexual irresponsibility” argument: in order to stay together, some opposite-sex couples need to feel the tingle they get from knowing that only their kind can get married. It makes them feel special and supported. This argument actually succeeded in persuading New York’s high court to deny a gay-marriage constitutional claim in 2006 in Hernandez v. Robles.

Posner made short work of the heterosexual irresponsibility argument. For Posner, the outcome in many cases should be decided by simply weighing costs and benefits. Indiana could not show how its interest in nudging heterosexual couples to marry was served by excluding same-sex couples from marriage. In the companion case challenging Wisconsin’s ban, Wolf v. Walker, the state’s attorney suggested that same-sex marriage might somehow “devalue” marriage, thus making it less attractive to opposite-sex couples. The “somehow” is key: incredibly, the Wisconsin lawyer said that he hadn’t studied how gays might ruin marriage for everyone else and hadn’t been prepared to argue about it. (It was only one of many times over two hours that the state attorneys seemed curiously incurious or unprepared.) So for Posner there was little or nothing on the “benefits” side of the ledger.

At the same time, there was plenty on the “costs” side. Posner pressed both states’ lawyers to concede the material and dignitary harm of gay-marriage bans on children being raised by same-sex couples. He seemed especially impressed by what he called the “harrowing” consequences detailed in an amicus brief filed by the Family Equality Council. Indiana’s attorney general finally conceded that the children of same-sex couples would “undoubtedly” be better off if their parents could marry. But neither the lawyer for Indiana nor Wisconsin seemed to have even considered the matter.

Posner dismantled the other arguments for banning same-sex marriage. He rejected as empty the idea that courts should simply defer to the democratic process. There had to be a rational basis other than that to sustain a law; otherwise, there would be no constitutional review. He dismissed as “feeble” the traditionalist concern that change on important policy questions should move slowly and incrementally. “How could that be a reason for anything?” he wondered. “They could have trotted out Edmund Burke in the Loving case.”

Posner scoffed at the notion that the state should be able to ban gay marriage even if it had no idea what harmful consequences, if any, might be caused. Exasperated, he finally asked the Wisconsin attorney to “speculate” about what the “possibilities” might be. “The harmful possibilities are, ‘We don’t know,'” replied the lawyer, echoing Charles Cooper’s famous response to Judge Walker on the harm of allowing same-sex marriage during the Prop 8 litigation. The exchange prompted Posner to quip, “You don’t have any sort of empirical or even conjectural basis for your law. Funny.” The same we-don’t-know fears would have justified continuing bans on contraceptives or prohibitions on inter-racial marriage, Posner noted.

Indiana agreed that discrimination against homosexuals would not serve any legitimate state interest in any other context. That’s reminiscent of another moment from the Prop 8 litigation, when Cooper conceded in oral argument before the Supreme Court that all discrimination against homosexuals was irrational. For his part, the Wisconsin attorney also acknowledged that the state was not concerned that gay marriage might turn heterosexuals into homosexuals. “That’s good,” Posner remarked.

On what basis might the panel vote to strike down the state marriage exclusions? All three judges were reluctant to rule that the bans violate the fundamental right to marry recognized in the Court’s substantive-due-process cases. In one of their few weak moments, the attorneys arguing for gay marriage were unable to articulate a convincing line on what marriages would have to be recognized as part of a fundamental right. Posner called the fundamental-rights doctrine a “morass.” The three judges also doubted that Windsor by itself compelled a certain result.

Judge Hamilton was taken with the sex-discrimination argument. His understanding of it seems more nuanced and sophisticated than other jurists’ since he gets both the formalist (it’s a sex classification) and substantive-sociological (it’s connected to the enforcement of traditional gender expectations) dimensions of the argument. Posner was unimpressed, noting that there are sex classifications throughout American law.

Although he didn’t mention it by name, Posner hinted at an animus holding. Why had the state of Indiana re-enacted its ban, he wondered, and then added mischievously: had the previous definition expired? The state banned same-sex marriage even though it couldn’t come up with a single plausible reason for the ban. “What’s that about?” Posner asked. There is a long history of “savage” discrimination against gay people, he observed. The ban on gay marriage, Posner concluded, is “based on hate, isn’t it?” Indeed, Posner has previously written that animus is the only explanation left when the state can offer no other real defense.

In many ways, the oral argument encapsulated the 25-year debate over same-sex marriage, in which  opponents have failed to come up with any harm that same-sex marriage might reasonably be expected to cause. Moreover, as in the larger debate over same-sex marriage, the lawyers for the states seemed not to have given any thought to the harm inflicted by bans on same-sex marriage because they had given little or no thought to the needs of families headed by same-sex couples.

Gay-marriage opponents have been backed into a vanishingly small empirical, logical, and legal corner in which they have no room to challenge the basic premises of gay equality, no ability to distinguish morally between homosexuality and heterosexuality and, in order to justify continuing to fence out gay couples, they must defend an understanding of the purpose of marriage that is so “artificially narrow” (Judge Hamilton’s phrase) and anemic it would be unrecognizable to the vast majority of Americans living in this or any other century.

Both arguments are well worth listening to. For those with limited time, some especially important exchanges come at about 12:30-24:30 in the Wolf argument.

UPDATE: For more on “the Posner treatment” see Ari Ezra Waldman’s terrific analysis here. Also see Art Leonard’s characteristically thorough and dispassionate review here.