The question raised and decided by the Connecticut Supreme Court and California's Supreme Court is whether civil unions, with the same rights and responsibilities on a state level as civil marriage, are a fair equivalent to civil marriage, under the rubric of equal protection of the laws. This is Obama's position. It is one on which I strongly disagree with him. My own explicit treatment of this particular aspect of the debate is in an essay published eight years ago in The New Republic. I stand by it. If you're interested, check it out.
I think the core resistance to marriage equality stems from a deep suspicion that gay men are incapable of the responsibilities of marriage and will taint it if allowed to own the name. (Tellingly, you almost never hear the same argument about lesbians, who make up a majority of same-sex marriages and tend to be more monogamous than straight couples.) But even this argument falters on inspection. Money quote:
Look at it this way. Even if you concede that gay men--being men--are, in the aggregate, less likely to live up to the standards of monogamy and commitment that marriage demands, this still suggests a further question: Are they less likely than, say, an insane person? A straight man with multiple divorces behind him? A murderer on death row? A president of the United States?
The truth is, these judgments simply cannot be fairly made against a whole group of people.
We do not look at, say, the higher divorce and illegitimacy rates among African Americans and conclude that they should have the right to marry taken away from them. In fact, we conclude the opposite: It's precisely because of the high divorce and illegitimacy rates that the institution of marriage is so critical for black America. So why is that argument not applied to homosexuals?
This, however, is to concede for the sake of argument something I do not in fact concede. The truth is that there is little evidence that same-sex marriages will be less successful than straight marriages. Because marriage will be a new experience for most gay people, one they have struggled for decades to achieve, its privileges will not be taken for granted. My own bet is that gay marriages may well turn out to be more responsible, serious, and committed than straight ones. Many gay men may not, in practice, want to marry. But those who do will be making a statement in a way no heterosexual couple now can. They will be pioneers. And pioneers are rarely disrespectful of the land they newly occupy. In Denmark, in the decade since Vermont-style partnerships have been legal, gays have had a lower divorce rate than straights. And that does not even take into account the fact that a significant proportion of same-sex marriages in America will likely be between women. If gay men, being men, are less likely to live up to the monogamy of marriage, then gay women, being women, are more likely to be faithful than heterosexual couples. Far from wrecking the neighborhood, gay men and women may help fix it up.