Today is the day of oral arguments in California Supreme Court, as justices hear challenges to Proposition 8, which passed by citizen vote last election.  Prop 8 prohibits gay marriages.

Four of the seven justices were convinced last spring that a prohibition on same-sex marriage violated a "fundamental constitutional right to form a family relationship."  But that is not the legal issue here. 

Bear with me now.  This isn't too complicated.

The central issue is about whether the change to the Constitution was procedurally legal, not whether the gay-marriage ban violates a "constitutional right".  Specifically, the justices must determine whether the Prop 8 initiative (which reads in full "Only marriage between a man and a woman is valild or recognized in California") represented an amendment to, or a revision of, the state Constitution.

It was presented to voters as an amendment, which can change the Constitution through the initiative process with a simple-majority vote of the people.

A revision, however, would need to be placed on the ballot with a two-thirds vote of the Legislature. The only other potential avenue for a revision would be for it to arise during a state constitutional convention.

The distinction, in simple terms, is between the tinkering of the constitution (amendment) and an overhaul of its fundamental underpinnings (revision).

Prop 8 opponents (i.e., gay marriage supporters) are making the argument that Prop 8 is (or should have been) a revision, not an amendment.  Prop 8 supporters, naturally, are trying to convince the court of the opposite.

So although four of seven justices were opposed to a prohibition on gay marriage, they were "overridden" by the electorate.  Now, the justices' task is to determine whether the electorate, as opposed to the Legislature and electorate, had the power to make that change in the first place. 

The amendment/revision issue is a different legal question, and the 4-3 split isn't (and shouldn't be) in play.  Of course, the amendment/revision issue touches on the whole "fundamental rights" issue, so the opinion is likely to discuss that at length.

In summation:

The pro prop. 8 arguments

• This is a constitutional amendment and it was properly filed and approved by voters
• It added just 14 words to the constitution and contains no redistribution of powers among the state's branches of government
• It's a simple constitutional change by the people in response to a ruling of the California Supreme Court

The against prop. 8 arguments

• This was a constitutional revision which was not filed properly — it should've been approved by a 2/3 vote of the legislature before going to voters.
• The court considers gay people a vulnerable class group shouldn't have rights stripped away by a slim majority.
• We're a democracy, but a constitutional democracy. There are checks and balances on majority power and the court must protect us all from the tyranny of the majority.

The "alternative" against prop. 8 argument (offered by ACLU and other gay rights groups)

• Some natural rights, like marriage, are completely inalienable and the people, by a majority vote, can't take them away from a minority and neither can the government – by a revision or amendment — without compelling justification. (This is what the CA Attorney General says and he finds some support in Article I of the California Constitution.)

What the court has already said

• Sure, gays are a "suspect" class (that means they've already be subject to discrimination in the past and likely will be again), and the California constitution, through its equal protection clause, guarantees all people the fundamental right to marry.
• But a constitutional revision has always been, at least to the court, something that "creates far-reaching changes in our government framework." most, prop. 8 doesn't seem to fit into the category.

The outcome?  Your guess is as good as mine, but I tend to think Prop 8 opponents will lose.  Prop 8 will not be recognized as a "revision", i.e., something that "creates far-reaching changes in our government framework."  The result will be a setback for gay marriage advocates, but rest assured, it won't be the end of the struggle.

The Court is required to issue a decision within 90 days of hearing the arguments, so a same-sex marriage ruling is expected by June.

UPDATE:  UMinn law professor Dale Carpenter watched the oral arguments to get a bead on where the justices were going:

I’ll predict without confidence that: (1) the court will hold that Proposition 8 was a valid amendment, but (2) will also hold that the 18,000 same-sex marriages entered between June and November continue to be recognized and valid in California.

It seemed to me that Chief Justice George and Justice Kennard, both in the 4-justice majority in last May’s marriage decision, were quite skeptical of the argument that Prop 8 was a revision requiring prior legislative approval. Maybe they were being devil’s advocates. But losing those two votes, if they’ve been lost, probably means losing on the challenge to Prop 8.

In principle, the justices’ votes on whether there is a right to same-sex marriage and on whether a proposition repealing that right is an amendment, are independent questions. A judge could believe there’s a fundamental right to same-sex marriage but that the state constitution liberally allows amendments by simple majority votes. On the other hand, a judge could believe there’s no fundamental right to same-sex marriage, but think that once the right is recognized, the elimination of a fundamental right for a suspect class is such a monumental act, and is fraught with so many dangers if allowed to stand as a precedent, that it can be accomplished only by revision.

The main hope, such as it remains, for opponents of Prop 8 lies in the recognition of several justices today, including at least one who dissented from last May’s decision, that Prop 8 is unprecedented and thus calls for a new articulation of what constitutes a revision.

He adds:

One more brief note from today’s argument. If it wasn’t clear before today, it is now clear that Attorney General Jerry Brown’s role in the case has not only been unhelpful to the petitioners, but has undermined it. His view is that Prop 8 is an amendment rather than a revision “under existing cases” but that Prop 8 is unconstitutional because it took away a right that is on an unspecified and growing list of “inalienable,” natural rights that can never be taken away by any constitutional change process. Brown thus undermines the petitioners on their strongest argument (the constitutional-procedural one) and offers instead a much weaker one (a constitutional-substantive one). It was plain in oral argument that none of the justices were buying it, and that Brown’s lawyer, given an impossible position to defend, could not defend it.