The briefs opposing gay marriage in the two cases currently under consideration in the Supreme Court are strange to say the least. Unlike past battles, the briefs do not argue that homosexuality is immoral. Major step forward. Sex is fine. Marriage is the problem.

Why? In short, because gay partnerships do not produce unwanted pregnancies.

Limiting marriage to opposite-sex couples is justified because it "reflect(s) a unique social difficulty with opposite-sex couples that is not present with same-sex couples — namely, the undeniable and distinct tendency of opposite-sex relationships to produce unplanned and unintended pregnancies. ... Unintended children produced by opposite-sex relationships and raised out of wedlock would pose a burden on society."

You read that right. Limiting marriage to opposite-sex couples prevents out-of-wedlock births. "It is plainly reasonable for California to maintain a unique institution (marriage) to address the unique challenges posed by the unique procreative potential of sexual relationships between men and women." Since same-sex couples "don't present a threat of irresponsible procreation," they don't need to get married.

Respectfully, this makes absolutely no sense. For one thing, heterosexual marriage does not prevent children from being raised by unwed mothers. If only. For another, the fact that gay couples do not have unintended pregnancies is hardly a reason they should not be allowed to marry. If only those who could have children were allowed to marry, there would be no reason to allow any woman over a certain age to marry.

And yet we do. Of course we do. My two favorite stories in last Sunday's New York Times Style Section, which reports on weddings and relationships (I am not the only one who calls it the ladies' sports page), report on late-life marriages. In one, there is a beautiful picture above the wedding announcement of a 97-year-old bride (she is keeping her name) and her 86-year-old groom, a widow and a widower who met five years ago.

The other is a first-person account by Eve Pell, who married when she was 71 and her husband-to-be was 81, titled "The Race Grows Sweeter Near Its Final Lap." They met when he was 77, because they belonged to the same running club, and she devised a plan with a mutual friend to invite him to a screening at the friend's home. Very "seventh grade," she wrote. "We had nothing to do but love each other and be happy. ... We followed our hearts and gambled, and for a few years, we had a bit of heaven on earth."

Neither of these marriages, like so many others, was necessary to serve the state's interest in promoting two-parent families. They were based, pure and simple, on what Pell calls "one of the most precious blessings available to human beings — real love."

Nearly half a century ago, the Supreme Court held that this blessing should not be limited to couples of the same race, as it had been in Virginia. In 2013, it is time for the Supreme Court to hold that it should not be limited to opposite-sex couples, any more than real love is.

This court does not want to be remembered as the court that decided the Dred Scott decision of its time: a case that held that a slave could not sue in federal court for his freedom, a case that is regarded in retrospect as one of the lowest moments in the history of the Supreme Court. I think the Chief Justice John Roberts knows that. I think Justice Anthony Kennedy, who wrote the landmark opinion in Lawrence v. Texas striking down Texas' sodomy laws, knows that.

I think the opponents of gay marriage are fighting a battle they will not win, and the weaknesses in the briefs filed by these distinguished lawyers reflect that.