Alex Brandon, Associated Press
This June 27, 2012 file photo shows an American flag flying in front of the Supreme Court in Washington.

WASHINGTON — After years of drama, the Supreme Court is poised to hear arguments on two pivotal same-sex marriage policies beginning Tuesday. On the docket are California's Proposition 8 and the federal Defense of Marriage Act, or DOMA, and lines for a gallery seat began forming as early as Friday.

As the court prepares to listen, pundits and experts are buzzing with warnings, fears and predictions.

As usual, eyes are focused firmly on the swing vote of Justice Anthony Kennedy. Kennedy is known to be sympathetic to gay rights claims, having written the majority opinions in Lawrence v. Texas and Roemer v. Evans.

Kennedy's thinking will likely hinge on his read of where society is shifting on the issue, Harvard law professor Michael Klarman wrote in an email to Richard Socarides at The New Yorker.

For Kennedy, Klarman argued, “the relevant questions would be whether the country is ready for this or whether a ruling in favor would generate too much backlash, and how much he cares about his legacy and how confident he is that within a relatively short period of time — a decade or so — a marriage equality ruling would be regarded as the Brown v. Board of the gay rights movement.”

With Kennedy at the pivot point, optimism among gay marriage supporters is high, based partly on shifting poll data. A report by the Pew Research Center released this month showed a dramatic shift in public opinion from 2003 to 2012, with opposition dropping from 58 to 44 percent. Forty-nine percent of Americans now support gay marriage, according to the poll.

Evan Wolfson, the president of the advocacy group Freedom to Marry, a gay rights group, expects that "both marriage cases will be good to great, rather than bad” for gay marriage advocates, he told Socarides at The New Yorker.

Wolfson believes that the “momentum we’ve been building has created a climate that says to the Justices they can do the right thing and know that not only will history vindicate them, but it will be true to where the American people already are.”

Wolfson's comments evoke a sentiment that while the court claims to decide cases based on legal principles, it is nonetheless very sensitive to social and political dynamics, often waiting for public opinion before making socially disruptive moves.

As George Will said in the Washington Post last week, the court also often invokes social science research to buttress legal claims. Will argued that relying on controversial research may be counterproductive on the gay marriage cases.

Will cites a lower court decision on Proposition 8 that cited child development specialist Michael Lamb, who argued that the “gender of a child’s parent is not a factor in a child’s adjustment” and that “having both a male and female parent does not increase the likelihood that a child will be well-adjusted.”

Will pointed to a brief filed with the court by conservative professors Leon Kass and Harvey Mansfield and the Institute for Marriage and Public Policy, which argued that Lamb had contradicted his findings in earlier research, in which he “had conceded that his own published research concluded that growing up without fathers had significant negative effects on boys” and “that traditional opposite-sex biological parents appear in general to produce better outcomes for their children than other family structures do.”

Will's argument against using social science research in court drew fire from gay rights advocates, who cast him as homophobic, although Will did argue that a decision grounded in the language of the equal protection clause would be more stable than one relying on social science.

"Such a victory for gay rights," Will concluded, "grounded on constitutional values, and hence cast in the vocabulary of natural rights philosophy, would at least be more stable than one resting uneasily on the shiftable sand of premature social science conclusions.”

Will's musings presuppose, in the case of California's Proposition 8, at least, that the court actually does make a decision on the merits of the case.

This is not a given, argues legal analyst Linda Greenhouse at the Washington Post.

Greenhouse focuses on the paradox that gay rights advocates are hoping that an ad hoc group fighting gay marriage will be granted "standing" by the court to represent the state of California in the Proposition 8 battle.

Standing is a judicial requirement that to do battle in court you have to demonstrate that you have been directly affected, or "injured," by the matter at hand.

After California decided not to defend its own law, a private group took up the battle, but if the court finds that this group lacks standing, then it could refuse to decide the case. This would confirm the status quo in California, with gay marriage legalized, but not create any sweeping changes across the nation.

Thus the paradox: gay marriage advocates want gay marriage opponents to win standing so that the court, led by Kennedy, can make a sweeping ruling.

"I happen to think the Proposition 8 supporters don’t have standing," Greenhouse wrote, "and that the justices will dismiss the appeal without reaching the merits. That would leave intact Judge Walker’s 2010 decision that Proposition 8 is unconstitutional."

Eric Schulzke writes on national politics for the Deseret News. He can be contacted at [email protected].