Fundamental rights in the United States in the context of "Same-sex marriage in the United States"

Substantive due process is a principle in United States constitutional law that allows courts to establish and protect substantive laws and certain fundamental rights from government interference, even if they are unenumerated elsewhere in the U.S. Constitution. Courts have asserted that such protections stem from the due process clauses of the Fifth and Fourteenth Amendments to the U.S. Constitution, which prohibit the federal and state governments, respectively, from depriving any person of "liberty ... without due process of law." Substantive due process demarcates the line between acts that courts deem subject to government regulation or legislation and those they consider beyond the reach of governmental interference. Whether the Fifth or Fourteenth Amendments were intended to serve that function continues to be a matter of scholarly and judicial discussion and dissent.

Substantive due process is to be distinguished from procedural due process. The distinction arises from the words "of law" in the phrase "due process of law". Procedural due process protects individuals from the coercive power of government by ensuring that adjudication processes, under valid laws, are fair and impartial. Such protections, for example, include sufficient and timely notice of why a party is required to appear before a court or other governmental body, the right to an impartial trier of fact and trier of law, and the right to give testimony and present relevant evidence at hearings. In contrast, substantive due process protects individuals against majoritarian policy enactments that exceed the limits of governmental authority: courts may find that a majority's enactment is not law and cannot be enforced as such, even if the processes of enactment and enforcement were actually fair.

Obergefell v. Hodges, 576 U.S. 644 (2015) (/ˈoʊbərɡəfɛl/ OH-bər-gə-fel), is a landmark decision of the United States Supreme Court which 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 of the Constitution. The 5–4 ruling requires all 50 states, the District of Columbia, and the Insular Areas under U.S. sovereignty to perform and recognize the marriages of same-sex couples on the same terms and conditions as the marriages of opposite-sex couples, with equal rights and responsibilities. Prior to Obergefell, same-sex marriage had already been established by statute, court ruling, or voter initiative in 36 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 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.