Obergefell v. Hodges, 576 U.S. 644 (2015) ( OH-br-g-fel), is a landmark civil rights case in which the Supreme Court of the United States ruled that the fundamental right to marry is guaranteed to same-sex couples by both the Due Process Clause and the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution. The 54 ruling requires all fifty states, the District of Columbia, and the Insular Areas to perform and recognize the marriages of same-sex couples on the same terms and conditions as the marriages of opposite-sex couples, with all the accompanying rights and responsibilities. Prior to Obergefell, same-sex marriage had already been established by law, court ruling, or voter initiative in thirty-six states, the District of Columbia, and Guam.Between January 2012 and February 2014, plaintiffs in Michigan, Ohio, Kentucky, and Tennessee filed federal district court cases that culminated in Obergefell v. Hodges. After all district courts ruled for the plaintiffs, the rulings were appealed to the Sixth Circuit. In November 2014, following a series of appeals court rulings that year from the Fourth, Seventh, Ninth, and Tenth Circuits that state-level bans on same-sex marriage were unconstitutional, the Sixth Circuit ruled that it was bound by Baker v. Nelson and found such bans to be constitutional. This created a split between circuits and led to a Supreme Court review.

Decided on June 26, 2015, Obergefell overturned Baker and requires all states to issue marriage licenses to same-sex couples and to recognize same-sex marriages validly performed in other jurisdictions. This established same-sex marriage throughout the United States and its territories. In a majority opinion authored by Justice Anthony Kennedy, the Court examined the nature of fundamental rights guaranteed to all by the Constitution, the harm done to individuals by delaying the implementation of such rights while the democratic process plays out, and the evolving understanding of discrimination and inequality that has developed greatly since Baker.

The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate and largely discretionary appellate jurisdiction over all federal and state court cases that involve a point of federal law, and original jurisdiction over a narrow range of cases, specifically "all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party." The Court holds the power of judicial review, the ability to invalidate a statute for violating a provision of the Constitution. It is also able to strike down presidential directives for violating either the Constitution or statutory law. However, it may act only within the context of a case in an area of law over which it has jurisdiction. The Court may decide cases having political overtones but has ruled that it does not have power to decide non-justiciable political questions.

Established by Article Three of the United States Constitution, the composition and procedures of the Supreme Court were initially established by the 1st Congress through the Judiciary Act of 1789. As later set by the Judiciary Act of 1869, the Court consists of the chief justice of the United States and eight associate justices. Each justice has lifetime tenure, meaning they remain on the Court until they die, retire, resign, or are removed from office. When a vacancy occurs, the president, with the advice and consent of the Senate, appoints a new justice. Each justice has a single vote in deciding the cases argued before the Court. When in majority, the chief justice decides who writes the opinion of the court; otherwise, the most senior justice in the majority assigns the task of writing the opinion.

The Court meets in the Supreme Court Building in Washington, D.C. Its law enforcement arm is the Supreme Court Police.