But in the end, the legal arguments being made at the Supreme Court today and tomorrow aren't why marriage equality will prevail (nor will contested social scientific findings matter in the long run). It's because public opinion is swinging definitively in favor of treating gays and lesbians as citizens with full rights in every possible situation. That in itself happened first and foremost by gays and lesbians who refused to be denigrated in all sorts of social, cultural, economic, and political situations, ranging from the anit-police riot at Stonewall through books, plays, movies, and even sitcoms that defended sexual preference as an individual right that the state or society writ large could dismiss either as pathological or criminal. Joe Biden, it turns out, was absolutely right when he said the Will & Grace had "probably did more to educate the American public [about tolerance for gays and lesbians] than almost anything anybody's ever done so far."

As can be seen from the growing number of national legislators - Republicans and Democrats alike - who are coming out in favor of same-sex marriage, law is often a trailing indicator of where public opinion is either headed or where it's already arrived. As law professor Mark Tushnet once told me, "The Court can have some influence on the margins, pushing things a little further in the direction that they're already moving or sometimes retarding the direction. But 10 years down the line, the society's going to be pretty much where it would've been even if the courts hadn't said a word about it."

The end of de jure racial segregation in post-War America is testament not just to how long and overdue the process of change can be; it also shows how messy it is, often bouncing back and forth between legal decisions, public opinion, and politics. But once large numbers people fall on one side of an issue - especially to a point where public denunciation and vilification of the minority group is no longer tolerated in polite society - the law will fall into line one way or another. And sooner rather than later.