"If California provides all the substantive benefits of marriage to same-sex domestic partnerships, are you seriously arguing that... if the case before us now were from a State that doesn't provide any of those benefits to same-sex couples, this case would come out differently?"

Justice Alito asked Ted Olson in the Prop 8 oral argument yesterday. Consider the problem of trying to narrow the case by limiting it to California, where voters amended the state constitution to restrict marriage to opposite-sex couples and where they permit civil unions that give gay people access to everything but the word "marriage."

There was much talk about the perversity of imposing more severe constitutional limitations on a state that has done much — but not everything — to include gay people and to give great leeway to the states that have excluded gay people altogether.

It does make some sense. The states that resist any inclusion have preserved arguments about the function of marriage that states like California have given up by structuring civil unions to provide almost equal treatment. It's hard to articulate a legitimate interest in only withholding the name.

But if the Court wants to leave the issue of same-sex marriage to the political process, why would it attach a consequence to taking the intermediate step of creating the civil unions category? That hampers the very process it would be purporting to enable.

ADDED: Later in the argument, Justice Scalia had this colloquy with Solicitor General Verrilli (who argued against Prop 8):

GENERAL VERRILLI: We are not … taking the position that it is required throughout the country. We think that that ought to be left open for a future adjudication in other States that don't have the situation California has.

JUSTICE SCALIA: So your -- your position is only if a State allows civil unions does it become unconstitutional to forbid same-sex marriage, right?

Amusingly, at exactly this point, Verrilli’s time’s-up red light comes on and he says” “It’s on.” He could have said, “Saved by the light!” But Chief Justice Roberts tells him to go on.

GENERAL VERRILLI: … I would just take out a red pen and take the word "only" out of that sentence. When that is true, then the Equal Protection Clause forbids the exclusion of same-sex marriage, and it's an open question otherwise.

In other words, to recapture that “only” and put it in a paraphrase: He’s only arguing now that his argument is limited to states like California. If he wins this case, in the next case, when the other issue is presented, he will argue that ssm is required everywhere. Anyone can predict that. Roberts pushes:

CHIEF JUSTICE ROBERTS: You [say] it's got to happen right now in California, but you don't even have a position about whether it's required in the rest of the country.

GENERAL VERRILLI: If -- with respect to a State that allows gay couples to have children and to have families and then denies the stabilizing effect.

What state doesn’t “allow” gay couples to have children and families? I can infer that Verrilli means allow adoption by gay couples, but it’s obvious that the concern about children extends to all the states, since a gay person can be a natural parent to a child and then live with a partner who is not the child’s parents.

Roberts doesn’t pursue that but sticks with his original point. Presumably, he's building the argument that it's incoherent to strike down Prop 8 without finding a right to ssm that applies to all the states.

CHIEF JUSTICE ROBERTS: So it's got to happen right away in those States where same-sex couples have every legal right that married couples do.

GENERAL VERRILLI: Well, we think… you can wait in…

CHIEF JUSTICE ROBERTS: States where they have fewer legal rights.

GENERAL VERRILLI: What I said is it's an open question with respect to those States and the Court should wait and see what kind of a record a State could make. But in California you can't make the record to justify the exclusion….

Verrilli is saying that the state that permits adoption by gay couples can’t go back to the argument that a child is better off having both a mother and a father in the home. Does this cure the incoherence? I doubt it. It's a distinction that might be employed by a judge who looks forward to extending ssm to all the states in the next case. I don't think Roberts is one of those judges.