WASHINGTON -- Late in the oral argument over same-sex marriage in California, Justice Anthony Kennedy made a startling comment, given the months of buildup and mountain of legal briefs that have descended on the justices.

"You might address why you think we should take and decide this case," Kennedy said to lawyer Charles Cooper, representing opponents of same-sex marriage.

One might have thought the court had already crossed that bridge.

But now the justices were openly discussing essentially walking away from the case over California's Proposition 8, a voter-approved ban on gay marriage, without deciding anything at all about such unions.

Indeed, this case offers a rare glimpse at the court's opaque internal workings, in which justices make cold political calculations about what to do and Kennedy's often-decisive vote can never be far from his colleagues' minds.

The court on Wednesday concluded two days of arguments involving gay marriage. In the second case, a constitutional challenge to a portion of the federal Defense of Marriage Act, a majority of the court appeared likely to rule that legally married gay couples should be able to receive a range of benefits that the law currently reserves for straight married couples.

The decision to hear the DOMA case was easy. The Supreme Court almost always has the final word when lower courts strike down a federal law, as they did in this case.

Proposition 8's route to the Supreme Court was not as obvious. The appeals court ruling under review by the justices seems to have been written to discourage the high court from ever taking up the case because it applies only to California and limited a much broader opinion that had emerged earlier from the trial court.

And yet in December, the court decided it would hear the case. It takes a majority of five to decide a case a particular way, but just four justices can vote to add a case to the calendar. And the court does not disclose how the justices vote at this stage.

It seems apparent after the argument, though, that it was the conservative justices who opted to hear Proposition 8. It also seems that one factor in their decision was that this could be their last, best opportunity to slow the nation's march toward recognition of gay marriage at a time when only nine states and the District of Columbia allow gays and lesbians to marry - despite a rapid swing in public opinion in favor of gay marriage.

From their comments and questions Tuesday, Justices Samuel Alito and Antonin Scalia indicated they preferred what they called the cautious approach: allowing the debate over gay marriage to play out in the states and not overturning by judicial fiat the will of California voters who approved Proposition 8 in 2008. Justice Clarence Thomas, as is his custom, said nothing during the argument, but he and Scalia were dissenters in the court's earlier two gay rights cases in 1996 and 2003.

Chief Justice John Roberts also had tough questions for lawyers for the same-sex couples who sued for the right to marry, and for the Obama administration.

Scalia sought to counter Kennedy's comment, and a similar one from Justice Sonia Sotomayor, that maybe the court should get rid of the case.

"It's too late for that, too late for that now, isn't it? I mean, we granted cert," Scalia said, using the legal shorthand for the court's decision to hear a case. "We have crossed that river, I think."

Once or twice a term, occasionally more often, the justices do dismiss cases after they have been argued, without rendering opinions and establishing a rule for the whole nation. The language they use is the wonderfully vague "dismissed as improvidently granted." Roughly translated, it means "sorry for wasting everyone's time."

That is one potential outcome, discussed publicly by Kennedy and Sotomayor.

Another possibility would be a decision limited to the technical legal question of whether the Proposition 8 supporters have the right to defend the measure in court. If they don't, the court can't reach the broader issues in the case.

On this point, Roberts' view seemed more in line with questions from some of the liberal justices.

So why would a justice who appeared favorably inclined to California's ban on gay marriage want to rule that the case should not even be in front of the court?

The answer is that Roberts might want to dispose of the case in this narrow way if he saw a decision in support of gay marriage emerging and wanted to block it. Or, he might choose this route if the justices appeared unable to reach a decisive ruling of any kind.

Narrowly based decisions sometimes seem more attractive to the justices than fractured rulings.

One example is the court's 2009 decision in a voting rights case in which eight of the justices agreed to sidestep the looming and major constitutional issue in the case after an argument in which the court appeared sharply split along ideological lines.

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