Mark Wilson / Getty Images A pro-gay-marriage banner is held in front of the Supreme Court in Washington on March 26, 2013

Justice Anthony Kennedy — widely viewed as the pivotal swing vote — got pulses racing early in today’s same-sex-marriage argument at the Supreme Court. There is “immediate legal injury” being done to 40,000 California children being raised by same-sex parents who are not allowed to marry, he insisted. These children “want their parents to have full recognition and full status,” he said — and “the voice of those children is important in this case.”

Court watchers immediately flooded Twitter and live blogs with the news: after that “vivid” comment, it was suddenly looking like there might be five votes — Justice Kennedy and the court’s four liberals — for a sweeping pro-gay-marriage ruling. But before long, Justice Kennedy seemed to reverse direction, openly questioning whether the court had made a mistake in accepting the case at all.

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Today’s oral arguments — in a challenge to California’s Proposition 8, which banned same-sex marriage — took place under a glaring national spotlight. Television cameras and throngs of reporters descended on the Supreme Court. Crowds of ordinary citizens gathered out front to express their views and to try to influence the Justices, in some cases with wacky signs in tow. (Sample: “Gays have every right to be as miserable as I make my husband.”) For months now, there has been a growing expectation that the Supreme Court would use this case to issue a landmark constitutional ruling, resolving for the history books whether same-sex couples have a right to marry.

But the Justices’ questions at oral argument suggested another possibility: that the Proposition 8 case may end not with a bang but with a hypertechnical legal whimper. It is always perilous trying to predict what the Supreme Court will do based on the Justices’ comments at oral argument, but it now may be that the likeliest outcome is a punt on the hard constitutional questions: the Justices may simply dismiss the case. That would most likely mean that a lower-court ruling invalidating Prop 8 would remain in effect — which would keep same-sex marriage legal in California but not affect other states.

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That is one way to count the votes at today’s oral argument: put Justice Kennedy with the court’s four conservatives, and there are not enough votes for a bold pro-gay-marriage ruling. It is not, however, the only way. At another point in the argument, Justice Kennedy said the case could take the court into “uncharted waters” or a “wonderful destination” — though he also worried that it could be a “cliff.” In that brief and highly contradictory comment — which is already being closely parsed — Justice Kennedy seemed to be deeply ambivalent: worried about the risks of a broad pro-same-sex-marriage ruling, while nevertheless excited about the possibilities.

The court will have another chance to wrestle with the question tomorrow, in a second case that challenges the Defense of Marriage Act, which bars the federal government from recognizing same-sex marriages and decrees that states do not have to recognize same-sex marriages performed in other states. That case, however, could well be resolved as a question of states’ rights or other legal doctrines that do not directly engage the key question of whether same-sex couples have a constitutional right to marry.

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Even some supporters of same-sex marriage think that a modest Supreme Court ruling — like one that allows same-sex marriages to continue in California but does not extend them further — could be a good thing. Political support for gay marriage continues to grow by the day — Senator Mark Warner of Virginia just got on board yesterday — and the momentum shows no sign of slowing. Advocates for a political solution argue that there will be less polarization and backlash if same-sex marriage gets adopted through the political process.

Appealing though that argument may be in some ways, it has serious flaws. If the Supreme Court fails to act, gay people in some parts of the country may have to wait many years before their home states recognize their right to marry — or they may have to move in order to marry. And rights that legislatures give they can also take away. Only the Supreme Court can declare that gay people have a fundamental constitutional right to marry — no matter what the politicians say.

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It is for these reasons that how Justice Kennedy comes down matters so much. Same-sex marriage is no longer the “uncharted waters” that he fears. We now have evidence from across the country that gay marriage has enormous upsides — including for the children Justice Kennedy rightly worried about — and no discernible downsides. Nondiscrimination is, in all its forms, a “wonderful destination,” as Justice Kennedy so aptly put it. By the time the Supreme Court’s term ends in late June, we will know if he proved courageous and forward-looking enough to lead the nation there.

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