Today is the first of two consecutive days of oral arguments about marriage equality cases at the Supreme Court. Come back to Reason.com later today for an interview with our own Damon Root, who is covering the arguments for us.

Here's a snippet from a Wall Street Journal op-ed by lawyers David Boies and Ted Olson, liberal and conservative legal eagles, on why California's Proposition 8, which killed same-sex marriage in the Golden State, should be overturned:

...laws like Proposition 8 cause devastating harm to gay and lesbian couples and their children. Exclusion from the institution of marriage marks those couples and their children with a badge of inferiority. The damage this does to their hearts and minds is immeasurable—and the damage it does to all of us and our belief in the nation's ideal of equality is incalculable.

For one to say that the Supreme Court should leave the question of marriage equality to the political processes of the states is to say that states should remain free to discriminate—to impose this pain and humiliation on gay men and lesbians and their children—for as long as they wish, without justification. The Constitution forbids such an indecent result. It did not tolerate it in separate schools and drinking fountains, it did not tolerate it with respect to bans on interracial marriage, and it does not tolerate it here.

Whole thing here.

(Hat tip: Instapundit)

Boies and Olson specifically argue that the 14th Amendment, which essentially applies the Bill of Rights to the states, means that state and local jurisdictions can't deny basic rights to individuals regardless of majority will or local preference. The 14th Amendment is a check on the states' power to be "laboratories of democracy" to allude to Justice Louis Brandeis' evocative phrase. And it's a good thing that power is checked, since as Root and many other have pointed out, the states are probably as often "laboratories of repression" as they are of anything else. Progressives such as Oliver Wendell Holmes Jr. and conservatives such as Robert Bork agree that, as Holmes' once put it, very little should get in the way of “the right of the majority to embody their opinions in law.” As Holmes put it back in the day, the 14th Amendment is "perverted...when it is held to prevent the natural outcome of a dominant opinion.” Yeesh.

There is real and ultimately irresolvable tension between the idea that individuals have certain rights that cannot be legislated away and the idea that the federal government's power should be limited. That's one point of disagreement among libertarians about marriage equality and a host of other issues, ranging from drug prohibition to college entrance policies and more. What counts as a fundamental right that should always and everywhere be respected - and what counts as something that can modified or even proscribed by a given unit of government (and under what circumstances)?

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 process began first and foremost because gays and lesbians refused to be denigrated in all sorts of social, cultural, economic, and political situations, ranging from the anti-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.

Watch last year's Why Gay Marriage is Winning: