The U.S. Supreme Court ruled on Friday that the U.S. Constitution provides same-sex couples the right to marry in a historic triumph for 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 ruling, gay marriage will become legal in all 50 states.
Justice Anthony Kennedy, writing on behalf of the court, said that the hope of gay people intending to marry "is not to be condemned to live in loneliness, excluded from one of civilization's oldest institutions.
"They ask for equal dignity in the eyes of the law. The Constitution grants them that right.
Today is a big step in our march toward equality. Gay and lesbian couples now have the right to marry, just like anyone else. #LoveWins— President Obama (@POTUS) June 26, 2015
"No union is more profound than marriage," he added.
The judgment will not take effect immediately because the court gives the losing side roughly three weeks to ask for reconsideration.
There are currently 13 state bans in place, while another state, Alabama, has contested a court ruling that lifted the ban there.
The ruling is the Supreme Court's most important expansion of marriage rights in the United States since its landmark 1967 ruling in the case Loving v. Virginia that struck down state laws barring interracial marriages.
The decision follows rapid changes in attitudes and policies toward gay marriage in America.
Gay marriage has gained increasing acceptance in opinion polls in recent years, particularly among younger Americans.
Two years ago, the Supreme Court struck down part of the federal anti-gay marriage law that denied a range of government benefits to legally married same-sex couples.
The decision in United States v Windsor did not address the validity of state marriage bans, but courts across the country, with few exceptions, said its logic compelled them to invalidate state laws that prohibited gay and lesbian couples from marrying.
There are about 390,000 married same-sex couples in the United States, according to Williams Institute at the University of California, Los Angeles, which tracks the demographics of gay and lesbian Americans.
Another 70,000 couples living in states that do not currently permit them to wed would get married in the next three years, the institute says, and roughly a million same-sex couples, married and unmarried, live together in the US.