On June 26, 2015, the Supreme Court issued its decision in Obergefell v. Hodges legalizing same-sex marriage throughout the country by requiring states to issue marriage licenses to same-sex couples and to recognize same-sex marriages that were legally formed in other states. In doing so, the Court resolved a circuit split regarding the constitutionality of state same-sex marriage bans. This report provides background on, and analysis of, significant legal issues raised by the Supreme Court's decision in Obergefell . It first offers background on the constitutional principles on which the Court relied in Obergefell to invalidate state same-sex marriage bans as unconstitutional. Then, it walks through the Court's opinion and rationale. Finally, it discusses potential implications of the Court's decision. Under the Fourteenth Amendment's Equal Protection Clause, "[n]o State shall … deny to any person within its jurisdiction the equal protection of the laws." Though there is no parallel constitutional provision expressly prohibiting the federal government from denying equal protection of the law, the Supreme Court has held that equal protection principles similarly apply to the federal government. Under the Constitution's equal protection guarantees, when courts review governmental action that distinguishes between classes of people, they apply different levels of scrutiny depending on the classification involved. The more suspect the government's classification, or the more likely that the government's classification was motivated by discrimination, the higher the level of scrutiny that courts will utilize in evaluating the government's action. Increased scrutiny raises the likelihood that a court will find the action unconstitutional. Generally speaking, there are three such levels of scrutiny: (1) strict scrutiny; (2) intermediate scrutiny; and (3) rational basis review. Strict scrutiny is the most demanding form of judicial review. The Supreme Court has observed that strict scrutiny applies to governmental classifications that are constitutionally "suspect," or that interfere with fundamental rights. In determining whether a classification is suspect, courts consider whether the classified group (1) has historically been subject to discrimination; (2) is a minority group exhibiting an unchangeable characteristic that establishes the group as distinct; or (3) is inadequately protected by the political process. There are generally three governmental classifications that are suspect—those based on race, national origin, and alienage. When applying strict scrutiny to governmental action, reviewing courts consider whether the governmental action is narrowly tailored to a compelling government interest. The government bears the burden of proving the constitutional validity of its action under strict scrutiny, and, in doing so, must generally show that it cannot meet its goals via less discriminatory means. Intermediate scrutiny is less searching than strict scrutiny, though it subjects governmental action to more stringent inspection than rational basis review. Intermediate scrutiny applies to "quasi-suspect" classifications such as classifications based on gender or illegitimacy. When reviewing courts apply intermediate scrutiny to governmental action, they determine whether the action is substantially related to achieving an important government interest. As with strict scrutiny, the government bears the burden of establishing the constitutional validity of its actions under intermediate scrutiny. Rational basis review is the least searching form of judicial scrutiny, and generally applies to all classifications that are not subject to heightened levels of scrutiny. For governmental action to survive rational basis review, it must be rationally related to a legitimate government interest. When evaluating governmental action under rational basis review, courts consider the legitimacy of any possible governmental purpose behind the action. That is, courts are not limited to considering the actual purposes behind the government's action. Additionally, the governmental action needs only be a reasonable way of achieving a legitimate government purpose to survive rational basis review; it does not need to be the most reasonable way of doing so, or even more reasonable than alternatives. Accordingly, rational basis review is deferential to the government, and courts generally presume that governmental action that is subject to such review is constitutionally valid. Parties challenging governmental actions bear the burden of establishing their invalidity under rational basis review. The U.S. Constitution's due process guarantees are contained within two separate clauses; one can be found in the Fifth Amendment, and the other resides in the Fourteenth Amendment. Each clause provides that the government shall not deprive a person of "life, liberty, or property, without due process of law." However, the Fifth Amendment applies to action by the federal government, whereas the Fourteenth Amendment applies to state action. The Constitution's due process language makes clear that the government cannot deprive individuals of life, liberty, or property without observing certain procedural requirements. The Supreme Court has interpreted this language to also include substantive guarantees that prohibit the government from taking action that unduly burdens certain liberty interests. More specifically, substantive due process protects against undue governmental infringement upon fundamental rights. In determining whether a right is fundamental, Supreme Court precedent looks to whether the right was historically and traditionally recognized, and whether failing to recognize the right would contravene liberty and justice. The Supreme Court has held that governmental action infringing upon fundamental rights is subject to strict scrutiny, and thus must be narrowly tailored to a compelling government interest. Under strict scrutiny, the government must generally show that it has a "substantial" and "legitimate" need for its action to be in furtherance of a compelling government interest. If the government successfully establishes a compelling interest, its action cannot encumber fundamental rights any more than is necessary to achieve the government's need. Additionally, the government could not have possibly taken alternative action that would similarly further its interest while being less burdensome on fundamental rights. Otherwise, the government's action is not narrowly tailored to the government's interest. The Supreme Court has recognized a number of rights as fundamental, including the right to have children, use contraception, and marry. In Obergefell , the Court considered whether the Fourteenth Amendment's substantive due process guarantees require states to issue marriage licenses to same-sex couples and require states to recognize same-sex marriages that were legally formed in other states. The Supreme Court resolved a circuit split on the constitutionality of state same-sex marriage bans, finding them unconstitutional in Obergefell v. Hodges . In doing so, the Court relied on the Constitution's due process and equal protection principles to hold that states must issue marriage licenses to same-sex couples and recognize same-sex marriages that were legally formed in other states. The majority in Obergefell rested its decision upon the fundamental right to marry. The Court observed that it has long found the right to marry to be constitutionally protected, though it acknowledged that its precedent describing the right presumed an opposite-sex relationship. Even so, according to the Court, these cases have identified reasons why the right to marry is fundamental, which apply equally to same-sex couples. These reasons included (1) personal choice in whom to marry is inherent in the concept of individual autonomy; (2) marriage's unique support and recognition of a two-person, committed union; (3) the safeguarding of children within a marriage, as both same-sex couples and opposite-sex couples have children; and (4) marriage as a keystone of the nation's social order, with no distinction between same-sex couples and opposite-sex couples in states conferring benefits and responsibilities upon marriages. Accordingly, the Court extended the fundamental right to marry to same-sex couples. In holding that the fundamental right to marry includes same-sex couples' right to marry, the Court appeared to acknowledge its departure from precedent for determining whether a right is fundamental—mentioned earlier in this report—which considers whether it is "deeply rooted in this Nation's history and tradition and implicit in the concept of ordered liberty." The Court observed that if rights were defined by who could historically use them, old practices could continuously prevent new groups from exercising fundamental rights. As such, the Court found that "rights come not from ancient sources alone. They rise, too, from a better informed understanding of how constitutional imperatives define a liberty that remains urgent in our own era." After determining that the fundamental right to marry includes the right of same-sex couples to marry, the Court also seemed to depart from precedent—and the approaches of courts of appeals that relied on the fundamental right to marry to strike down state same-sex marriage bans—by not applying strict scrutiny to such bans. As previously noted, courts generally subject governmental action that infringes upon a fundamental right to strict scrutiny, requiring that the action be narrowly tailored to a compelling government interest to be constitutional. The states had argued two primary interests for their bans on same-marriage: (1) the desire to wait and see how the same-sex marriage debate progresses before changing long-existing marriage norms; and (2) incentivizing procreating couples to stay together during child rearing. However, the Court made no mention of whether the state same-sex marriage bans at issue were narrowly tailored to these justifications. Rather, the Court noted why these justifications were invalid without appearing to apply any of the typical levels of judicial review (i.e., rational basis review, intermediate scrutiny, or strict scrutiny). The Court held that both equal protection and due process guarantees protect the fundamental right to marry, and that states can no longer deny this right to same-sex couples. Importantly, in doing so, the Court did not hold that classifications based on sexual orientation warrant any form of heightened scrutiny. In fact, the Court made no mention of the proper level of scrutiny applicable to such classifications. Some of the dissenting Justices in Obergefell thought that the majority exceeded the Court's proper role by removing the question of whether same-sex couples have the right to marry from the democratic process, where, they stated, it is properly resolved. According to these Justices, the five-person majority should not have resolved the hotly contested issue of same-sex marriage for the entire country; such resolution should have come from the people. The dissenting Justices also voiced concern with the majority looking beyond history and tradition to establish a fundamental right contrary to Supreme Court precedent.