Supporters of gay marriage wave the rainbow flag after the US Supreme Court in Washington ruled yesterday that the US Constitution provides same-sex couples the right to marry. Photo: Reuters

The Supreme Court ruled yesterday that the US Constitution provides same-sex couples the right to marry, handing a historic triumph to the American gay rights movement.

The court ruled 5-4 that the Constitution’s guarantees of due process and equal protection under the law mean that States cannot ban same-sex marriages. With the landmark ruling, gay marriage becomes legal in all 50 States.

Immediately after the decision, same-sex couples in many of states where gay marriage had been banned headed to county clerks’ offices for marriage licences as state officials issued statements saying they would respect the ruling.

President Barack Obama hailed the ruling as a milestone in American justice.

“This ruling is a victory for America,” said Obama, the first sitting President to support gay marriage.

Justice Anthony Kennedy, on behalf of the court, said the hope of gay people intending to marry “is not to be condemned to live in loneliness, excluded from one of civilisation’s oldest institutions. They ask for equal dignity in the eyes of the law. The Constitution grants them that right.” Kennedy, a conservative who often casts the deciding vote in close cases, was joined in the majority by the court’s four liberal justices.

Five unelected judges have redefined the foundational unit of society

Kennedy, appointed by Republican President Ronald Reagan in 1988, has now authored all four of the court’s major gay rights rulings, with the first coming in 1996. As with his 2013 opinion when the court struck down a federal law that denied benefits to same-sex couples, Kennedy stressed the dignity of marriage.

Meanwhile in a blistering dissenting opinion, conservative Justice Antonin Scalia said the decision shows the court is a “threat to American democracy.” The ruling “says that my ruler and the ruler of 320 million Americans coast-to-coast is a majority of the nine lawyers on the Supreme Court,” Scalia added.

Conservative Chief Justice John Roberts read a summary of his dissent from the bench, the first time he has done so in his 10 years on the court. Roberts said that, although there are strong policy arguments in same-sex marriage, it was not the court’s role to force States to change their marriage laws.

“Five lawyers have closed the debate and enacted their own vision of marriage as a matter of constitutional law,” Roberts wrote.

Although the ruling only affects State laws and religious institutions can still choose whether to marry same-sex couples, Roberts predicted future legal conflicts.

“Hard questions arise when people of faith exercise religion in ways that may be seen to conflict with the new right to same-sex marriage,” Roberts said.

He gave as an example a religious college that provides married student housing only to opposite-sex couples.

The ruling is the latest milestone in the gay rights movement in recent years. In 2010, Obama signed a law allowing gays to serve openly in the US military.

In 2013, the high court ruled unconstitutional a 1996 US law that declared for the purposes of federal benefits marriage was defined as between a man and a woman.

Conservatives denounced the ruling. Republican presidential candidate Mike Huckabee said, “This flawed, failed decision is an out-of-control act of unconstitutional judicial tyranny.” Republican presidential candidate Rick Santorum lamented that five “unelected judges redefined the foundational unit of society.”

Opponents say same-sex marriage legality should be decided by States, not judges. Hillary Clinton, front-runner for the 2016 Democratic presidential nomination, wrote on Twitter she was “proud to celebrate a historic victory for marriage equality.”