WASHINGTON — Supreme Court justices considered the deepest meanings of marriage Tuesday and the civil-rights consequences of denying lesbians and gays the benefits of matrimony, even as some of the justices questioned during oral arguments whether Americans are ready for the nation’s highest court to settle the emotional, rapidly evolving issue.
As the court kicked off two days of historic deliberations on gay marriage, drawing supporters and opponents to the courthouse steps, the possible swing vote, Justice Anthony Kennedy, struck a cautious note. He questioned the wisdom of upholding or overturning California’s Proposition 8 constitutional amendment, which banned the practice in the state.
The court would be entering “uncharted waters” with such a move, Kennedy said, expressing concern about moving too fast on a subject for which public opinion is in flux and societal consequences are unknown.
“We have five years of information to weigh against 2,000 years of history or more,’’ he said.
Justice Samuel Alito, too, spoke on the novelty that people of the same sex could wed, a concept “newer than cellphones or the Internet.”
“We do not have the ability to see the future,” Alito said. “On a question like that, of such fundamental importance, why should it not be left for the people, either acting through initiatives and referendums or through their elected public officials?”
Even Justice Sonia Sotomayor, considered one of the more liberal justices, asked why taking the case now is the answer, if the issue is allowing states to experiment and giving society time to figure out its direction.
The questions created doubt about whether the court would issue a broad ruling in June and establish the constitutional right for gays to marry in all states. But it is notoriously difficult to discern from oral arguments how the court will rule.
“They’re getting into the question of whether the Constitution is something that reflects changing social mores,” said Michael Klarman, a Harvard law professor whose book “From the Closet to the Altar: Courts, Backlash, and the Struggle for Same-Sex Marriage” was published in October.
“Social change happens in a gradual way. At one point it’s something most of the country is opposed to, but public opinion comes around and ultimately it gets to a point where most people support the change,” said Klarman, whether it’s interracial marriage, school desegregation, abortion, or gay marriage. “The question is where the court intervenes along that spectrum.”
While Kennedy expressed skepticism about the timing and appropriateness of a court ruling on gay marriage, he also suggested that not allowing such unions would cause “immediate legal injury” to the 40,000 children in California living with same-sex parents.
“They want their parents to have full recognition and full status,” Kennedy said. “The voice of those children is important in this case.”
The court will confront similar challenges on Wednesday when it takes up the 1996 Defense of Marriage Act. Instead of considering a state referendum, it will consider a law of Congress that bars married gay couples from receiving federal marriage benefits such as spousal disability, Social Security, and family medical leave.
The justices also considered whether marriage itself is an institution defined by a couple’s sex and tied to producing children, and whether redefining it could harm society.
Charles Cooper, the attorney arguing on behalf of gay marriage opponents, said marriage between a man and a woman is in the best interest of society because only such a union could lead to “responsible procreation.” Since gay couples do not have the biological capacity to produce children together, the equal protection clause under the constitution does not apply to them, he argued.
“The concern is that redefining marriage as a genderless institution will sever its abiding connection to its historic, traditional, procreative purposes,” Cooper argued, “and it will refocus the purpose of marriage and the definition of marriage away from the raising of children and to the emotional needs and desires of adults.”
In a debate over the purpose of marriage, Justice Elena Kagan compared denying gays and lesbians the right to marry with denying couples over age 55 a marriage license simply because of their slim chances of bearing children. “If you’re over the age of 55, you don’t help us serve the government’s interest in regulating procreating through marriage,” Kagan said. “So why is that different?”
Justice Ruth Bader Ginsburg asked why a prisoner, locked behind bars with no possibility of procreating, should then have a right to marry.
Voters in California banned gay marriage six months after the state Supreme Court endorsed such unions. The state’s constitution was amended to recognize marriages only between a man and a woman.
Theodore Olson, the attorney for two California couples challenging the ban, said the amendment unfairly discriminates by walling gays and lesbians off from the institution of marriage, which he argues is an individual right. Procreation is not a fundamental part of marriage, he said.
Heterosexual couples have always been allowed to marry whether or not they intend to have children.
“There are lots of people who get married who can’t have children,” said Justice Stephen Breyer.
Olson tangled with Justice Antonin Scalia, who challenged him repeatedly to answer when it became unconstitutional to prohibit homosexuals from marrying. Scalia asked him whether the case would stand if the California amendment were enacted before the court allowed gay marriage.
Solicitor General Donald Verrilli Jr.also urged that the California ban be struck down because the state has extended all substantive rights and responsibilities of marriage to gay and lesbian domestic partners.
A broad ruling establishing gay marriage rights under the Constitution is, though considered unlikely, one possible outcome. The court could decide on more limited grounds to uphold the lower-court decision, effectively ending the ban in California but not establishing a broader precedent for other states. The court also could reverse the lower-court decision against Proposition 8 and reinstate California’s ban on gay marriage, which would be a huge victory for opponents of gay marriage. It could also dismiss the case.
“It’s extremely unlikely the court is going to give a broad ruling recognizing the fundamental right to marry in all 50 states,” said Linda McClain, a Boston University law professor who specializes in legal issues involving family and gender. “Even the liberal members of the court are going to be worried about moving so rapidly about an issue.”
Massachusetts became the first state to legalize gay marriage in 2003. Eight other states, plus the District of Columbia, have followed suit. But 31 states have imposed bans.
Support for gay marriage has grown to an all-time high of 58 percent, according to a Washington Post-ABC News poll published last week. That is a dramatic flip from 2010, when more opposed same-sex marriage than supported it.
Gay marriage supporters and others intent on witnessing history slept in line outside the Supreme Court for five days, through rain and snow, for a coveted public seat inside the courtroom. Others spent the night to secure prominent posts in front of the courthouse steps.
For J. Mary Sorrell, who said she became Massachusetts’ first openly lesbian justice of the peace in 2004 and has officiated the weddings of gays from around the world, “There is nowhere else I’d rather be. This is the civil rights issue of our day, and I don’t take it for granted.”
Sorrell, of Williamsburg, said that when gay marriage was allowed in Massachusetts, “I could feel there would be reverberations way beyond our little Commonwealth. But I didn’t think that just nine years later we’d be here at the Supreme Court oral arguments.”
President Obama, who in May became the first president to announce support for gay marriage, has said he thinks the Defense of Marriage Act is unconstitutional and his administration has not defended it.Tracy Jan can be reached at email@example.com. Follow her on Twitter @GlobeTracyJan.