Kennedy said same-sex couples were seeking the same dignity as heterosexual couples.

(Bloomberg) — A pivotal justice sent mixed signals as the U.S. Supreme Court heard arguments in a historic case that could legalize gay weddings nationwide.

Justice Anthony Kennedy said same-sex couples were seeking only the same “dignity” and “ennoblement” as heterosexual couples. Earlier, he offered hope to same-sex marriage opponents who argue that marriage should be defined as between a man and a woman.

“This definition has been with us for millennia,” Kennedy said. It’s difficult for the Supreme Court to say “we know better,” he asked.

Chief Justice John Roberts also aimed questions at both sides during the first part of the court’s 2 1/2 hour argument.

The “basic definition” of marriage is between a man and woman, Roberts said. While acceptance of same-sex marriage has occurred relatively quickly, people feel “very differently” about issues they have an opportunity to vote on rather than having a policy imposed by a court, the chief justice said.

“You’re seeking to change what the institution is,” Roberts told a lawyer for gay-marriage proponents. “If you prevail here, there will be no more debate.”

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As the state of Michigan presented its case in favor of state bans on gay marriage, Roberts also questioned that position.

“If Sue loves Joe and Tom loves Joe, Sue can marry Joe but Tom cannot,” Roberts said. “Why isn’t that a straightforward case of sexual discrimination?”

Critical vote

Kennedy is a critical vote for marriage advocates. He wrote all three of the court’s rulings expanding gay rights over the last two decades, including the 5-4 decision two years ago that required the federal government to recognize same-sex marriages.

The Obama administration’s Solicitor General Donald Verrilli said the Constitution’s equal-protection guarantee should apply, giving gay couples access to the institution.

Gay-marriage opponents are saying “that with regard to marriage they are not ready yet,” Verrilli said. “Gay and lesbian people are equal, they deserve equal protection of the law and they deserve it now.”

As Verrilli rose to speak, a protester interrupted the proceedings, shouting that supporters of gay marriage will “burn in hell.” Police officers removed the protester from the courtroom.

Justice Scalia

Justice Antonin Scalia said a ruling that same-sex couples have a constitutional right to marry would be “unpalatable to many of our citizens for religious reasons.”

Justice Samuel Alito asked whether states would have to sanction marriages between siblings or among a group of four people if it extended marriage to same-sex couples.

A decision backing gay marriage would be the culmination of a decades-long movement that has rapidly gained momentum in the past dozen years. The number of states where gays can legally wed has tripled in two years to 36, and advocates want the high court to extend that to the remaining 14 states.

Polls show record support among Americans for same-sex weddings. Hundreds of companies — among them, Goldman Sachs Group Inc., Google Inc. and Walt Disney Co. — are supporting gay marriage.

31 adults

The high court is hearing cases from Michigan, Kentucky, Ohio and Tennessee — the states covered by a federal appeals court ruling that rejected marriage rights.

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Among the 31 adults pressing suits are April DeBoer and Jayne Rowse, nurses who have adopted four children, two of them with special needs, and are seeking to marry in Michigan. The Ohio case includes Jim Obergefell, who seeks to have his name on the death certificate of his partner of two decades, John Arthur. Obergefell and Arthur married on an airport tarmac in Maryland in 2013 just months before Arthur’s death.

The argument follows weeks of advocacy and anticipation, evidenced by the 140-plus briefs the court received from outside groups and individuals. The line for at least 50 public seats in the courtroom began forming outside the Supreme Court Friday morning. As the argument hour neared Tuesday morning, marriage advocates danced and waved rainbow flags while opponents held signs decrying homosexuality.

The lead case is Obergefell vs. Hodges (Case Number 14-556(.

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