1967. That was the year, barely half a lifetime ago, when the Supreme Court handed down its landmark decision in

Loving v. Virginia,

ruling that laws against interracial marriage unconstitutionally violated one of the "basic civil rights of man." That such legislation, so archaic, so baldly contrary to the founding principles of our nation, was the law of the land in so many states until so recently is remarkable.

When it comes to the right of gay and lesbian couples to be married, that similar discriminatory legislation is still the law of the land in so many states is tragic.

To be sure, gay marriage is no longer the presidential campaign wedge issue it was in 2004; with the country still facing economic straits, there is more than enough fodder for divisive pandering. At the same time, popular opinion on marriage equality has changed significantly (if not sufficiently) in the past few years, as a recent Pew study shows: In 2001, Americans opposed same-sex marriage, 57 percent to 35 percent. Today, virtually as many Americans support it as oppose it.

This shift offers an encouraging sign that prejudice against a vulnerable class of Americans is waning. Indeed, a handful of states recognize marriages between same-sex couples as affording the same rights as those between opposite-sex couples. In those states (and the District of Columbia) where gay marriage has been legalized through either legislative or judicial action, we have yet to hear of a single heterosexual marriage torn asunder as a result.

Still, is it enough to expect that the success of a few state-level experiments with marriage equality will spread to the rest of our nation's "laboratories of democracy" sooner or later? If the civil rights struggles of the 1960s taught us anything, it's that "later" is never an acceptable answer to such questions. As long as same-sex couples are relegated to second-class status, not only will a fundamental constitutional injustice persist, but so will lasting damage to real people and their sense of self-worth.

While no scientific research shows that legalization of gay marriage causes psychological harm, evidence indicates that its absence does. A 2009 article in the American Journal of Public Health concluded that statewide "discriminatory policies may have pernicious consequences for the mental health of LGB populations" by leading to higher incidences of mood disorders, alcoholism, and anxiety. Even if we look beyond the physical and psychological injury that this institutionalized discrimination visits upon a particular segment of Americans, the endurance of this sad status quo prevents our nation as a whole from living up to that axiom enshrined in our Declaration of Independence "that all men are created equal."

The position, popular among elected officials these days, that gay and lesbian Americans deserve fair treatment under the law so long as marriage is not "redefined" reflects the move in public opinion toward tolerance, but the stance remains constitutionally incoherent. Theodore Olson, a conservative legal icon who served as George W. Bush's solicitor general, is now fighting to overturn a 2008 California referendum that ended that state's attempt to legalize gay marriage. He has eloquently written that "the very idea of marriage is basic to recognition as equals in our society; any status short of that is inferior, unjust, and unconstitutional."

Though domestic partnership and civil-union laws are arguably a correct step in the general direction of equality, they are by no means the end of the journey. These sorts of statutes, while they do afford same-sex partners some of the rights granted heterosexual married couples, are at bottom nothing more than another iteration of antiquated "separate but equal policies," which are not equal at all. Until same-sex marriages are fully recognized, the message our government sends to our gay and lesbian fellow citizens is that they are, and deserve, less than the rest of us.

Our president, whose own views on gay marriage are "evolving," is fond of quoting Martin Luther King Jr., who said, "The arc of the moral universe is long but it bends toward justice." On the matter of equality for all Americans, regardless of sexual orientation, we need to acknowledge that this moral arc has bent long enough. Now is the time for justice.