Tom Goldstein of SCOTUSblog tweets, during the short break after the first hour of argument in the California Prop 8 case, that …

Breaking: 1st update- #prop8 unlikely to be upheld; either struck down or #scotus won’t decide case. More in 30 mins.
This is the more important of the two gay-marriage cases.  Tomorrow’s argument will be on the constitutionality of the federal Defense of Marriage Act (DOMA), but almost no one (best as I can tell), thinks the Court will uphold the constitutionality of that Act.  The real suspense* is in the Prop 8 case.  So ….

UPDATE: Here’s Tom Goldstein’s post-argument report.

SECOND UPDATE: This one’s from Reuters. It seems to me that the Roberts comment quoted in the article is very significant. In a good way.

THIRD (and final, for at least a few hours) UPDATE: Here’s SCOTUSblog’s Lyle Denniston’s take.  He’s my (and many, many others’) go-to guy on all things Supreme. He seems to think that they’ll simply dismiss the Supreme Court case, saying that the petition grant was “improvidently granted,” leaving the Ninth Circuit opinion intact.

That would leave intact the Ninth Circuit ruling–which was that, because California already had been allowing same-sex marriage before Prop. 8 was approved in 2006, in localities that approved it, the state could not suddenly render those marriages null and void.  Doing so would violate the Fourteenth Amendment’s Due Process clause.  And since some gays already were allowed to be married, and their marriages would continue to be recognized by the state, refusing to allow other gays to marry would violate the Fourteenth Amendment’s Equal Protection clause. That’s the ruling that would remain in effect if the Supreme Court rules that the Prop. 8 petitioners have no legal standing to be a party to the case.  

That now seems more likely to me than the other option that would allow them to avoid deciding on whether same-sex marriage is a constitutional right.  That other option would be to rule that “the petitioners”–the group that earlier asked the Ninth Circuit, and then asked the Supreme Court, to “vacate” the lower-court rulings and uphold the constitutionality of Prop. 8–don’t have “standing” to be a party to the lawsuit, because they would have no injury from a court ruling striking down Prop. 8 that is sufficiently direct and significant to meet the Article III standing requirement.  

If they go the “no standing” route, that would leave intact not the Ninth Circuit ruling based on narrow grounds but instead the lower, trial-court judge’s ruling, which was based on much broader grounds.  The effect would be somewhat, but not entirely the same, whichever of these two options they choose.

As I understand it, if they choose the option that leaves the Ninth Circuit opinion in place, that would mean that localities in California would have the option to allow same-sex marriage but would  not be required to allow it, although all government entities throughout the state would have to recognize any same-sex marriage as legal. If they instead choose the option that vacates the Ninth Circuit opinion and restores the lower, trial-court ruling, by ruling that the petitioners have, and had, no legal standing to appeal from the trial-court ruling either in the Ninth Circuit Court of Appeals or in the Supreme Court, that would mean that, for now, in central California, within the trial-court level federal court district where the case was filed and where the trial-court ruling was issued, Prop. 8 would be invalid and all localities within that court district would be required to allow same-sex marriage.

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*Originally, I used the word “action,” but changed it to “suspense” because, if the Court strikes down DOMA as unconstitutional, that would be big, important action. I really meant “suspense,” because I do think the striking of DOMA is highly likely; not much suspense on that. But tomorrow’s argument will give some hint about whether I’m right.