This is a point about one way that law changes. Gay marriage will, obviously, soon be the law of the land. It’s coming down to a question of this year or the next few, not decades. This legal revolution owes to a combination of things: broad social forces, the legal legacy of the civil rights era, popular entertainment, and, most of all, the courageous acts of gay people who have come out to their friends and family. But just how much has changed can be heard in the remarkable oral argument in the Seventh Circuit, in which a very hostile Judge Posner lambasts lawyers defending the Wisconsin and Indiana marriage bans.

Listen to excerpts here or the whole arguments here and here. Posner’s basic point was: why? What reason is there to have such a law? The answers given were, to put it charitably, unconvincing. They boil down to two: (1) The will of the people as enacted by the democratically elected legislature should be respected by judges, and (2) the long history and tradition of this particular discrimination should give judges great pause before dismantling it. The latter adverts to a Burkean avoidance of upsetting traditions for fear of the unintended consequences that may follow. Perturbing a stable and complex system should be done with caution. As Burke put it: “that which in the first instance is prejudicial may be excellent in its remoter operation” and that “it is with infinite caution that any man ought to venture upon pulling down an edifice which has answered in any tolerable degree for ages the common purposes of society.” (Note also that Burke himself likely would have sharply rejected the first reason.)

Posner ridiculed these two reasons at oral argument. The first could be interposed against any claim that a statute is unconstitutional and so would be doing no work additional to existing doctrines of judicial deference, doctrines that demand at least some plausible reason for a discrimination. The second could be be lodged against any effort at legal change and, for Posner’s part, would need at least some plausible guess about what might go wrong in order to be even mildly persuasive. For example, it is easy and not unreasonable to speculate that moving to no-fault divorce could, even in the absence of experience with such a regime, increase the number of divorces and cause bad social consequences. Whether that potential harm would justify foregoing the benefit that would come with change is a different question, but at least one could give a speculative reason to be cautious. The lawyers were unwilling or unable to identify any concrete harms that allowing gays to marry might cause.

Thirty years ago, the state’s lawyers would have had lots of responses to Posner’s questions. Most would have been variations on the themes of the possibility of gay contagion and the perceived ickiness of gay sex. They would have been the formalized and sanitized versions of then-common locker room jokes and solemn acknowledgments of the truths we all know deep down. And they would have won the day, because it was simply inconceivable to many that “the gay lifestyle” should be decriminalized, much less tolerated, and much, much less respected.

Here is what Chief Justice Burger wrote in Bowers v. Hardwick, concurring in order to emphasize the constitutionality of a criminal prohibition on having gay sex in one’s own home:

Decisions of individuals relating to homosexual conduct have been subject to state intervention throughout the history of Western civilization. Condemnation of those practices is firmly rooted in Judeo-Christian moral and ethical standards. Homosexual sodomy was a capital crime under Roman law. During the English Reformation, when powers of the ecclesiastical courts were transferred to the King's Courts, the first English statute criminalizing sodomy was passed. Blackstone described "the infamous crime against nature” as an offense of "deeper malignity" than rape, a heinous act "the very mention of which is a disgrace to human nature," and "a crime not fit to be named." The common law of England, including its prohibition of sodomy, became the received law of Georgia and the other Colonies. In 1816, the Georgia Legislature passed the statute at issue here, and that statute has been continuously in force in one form or another since that time. To hold that the act of homosexual sodomy is somehow protected as a fundamental right would be to cast aside millennia of moral teaching.

(Citations have been omitted.) These arguments, which stand for more than the raw fact that long-dead people made them but clearly ask that we accept their conclusions, call us to moral consensus. These kinds of responses, however, are now ruled out as bigoted, because they are clearly and deeply insulting to the gay friends and relatives that almost all of us now know that we have and whose sex lives we now think no more icky than any one else’s — and certainly less icky than many other sexual preferences the internet has foisted on the general consciousness. And so the marriage dead-enders are left with bare history and tradition, lacking any reasons one should agree with that history and those traditions.

To be clear, from the date of their writing, Burger’s arguments offended certain principles about just treatment, minority protection, and religious equality. See, e.g., Justice Blackmun's dissent. They were odious from the start in my view. But they now offend the basic political consensus. Someone making these same arguments at a dinner would cause those around them to become very uncomfortable. Maybe not in every social circle but in enough that we all know how this social struggle will end.

And so we come to the point of this post, to observe a way law can change without the amendment of words of statutes or the text of the Constitution. Here, the law being applied is the same as it has been: To be upheld, a discrimination in a law requires some justification, even if only barely rational. But the only justifications that can be considered free-standing reasons cannot be uttered in polite company these days. The lawyers defending these laws almost certainly do not want to make them and probably do not believe them. The law on gay marriage is about to change not (only) because the constitutional approach to such laws is now different but because the old arguments have been rendered unavailable by a dramatic change in social norms. Gays are now firmly within the community of equals. That is a social fact as well as a political decision, and courts are now being asked to ratify it with nothing substantial to oppose it.