In a landmark decision, the U.S. Supreme Court held that the Fourteenth Amendment requires states to license marriages between two people of the same sex and to recognize same sex marriages that were validly licensed in other states. The decision in Obergefell v. Hodges, written by Justice Kennedy, overturned a decision by the U.S. Court of Appeals for the Sixth Circuit, which had upheld the constitutionality of same-sex-marriage bans in four states. Four Justices dissented.

The majority opinion discussed "the transcendent importance of marriage" in society and "the centrality of marriage to the human condition." It concluded that those petitioning for same sex marriage rights do not seek to devalue marriage but "seek it for themselves because of their respect and need for its privileges and responsibilities." Although the Court affirmed "[t]he ancient origins of marriage," it also concluded that "[t]he history of marriage is one of both continuity and change. That institution—even as confined to opposite-sex relations—has evolved over time."