Early in the history of the United States, the Supreme Court began to exercise the power that it is most closely and famously associated with—its authority of judicial review. In its 1803 decision in Marbury v. Madison , the Supreme Court famously asserted and explained the foundations of its power to review the constitutionality of federal governmental action. During the two decades following its holding in Marbury , the Court decided additional cases that helped to establish its power to review the constitutionality of state governmental action. If a challenged governmental action is unconstitutional, the Court may strike it down, rendering it invalid. When performing the function of judicial review, the Court must necessarily ascertain the meaning of a given provision within the Constitution, often for the first time, before applying its interpretation of the Constitution to the particular governmental action under review. The need to determine the meaning of the Constitution through the use of methods of constitutional interpretation and, perhaps, construction, is apparent from the text of the document itself. While several parts of the Constitution do not lend themselves to much debate about their preferred interpretation, much of the Constitution is broadly worded, leaving ample room for the Court to interpret its provisions before it applies them to particular legal and factual circumstances. For example, the Second Amendment reads, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." The text of the Amendment alone does not squarely resolve whether the "right of the people to keep and bear arms" extends to all citizens or merely is related to, or perhaps conditioned on, service in a militia. This ambiguity prompted a closely divided 2008 decision of the Supreme Court that ruled in favor of the former interpretation. The text of the Constitution is also silent on many fundamental questions of constitutional law, including questions that its drafters and those ratifying the document could not have foreseen or chose not to address. For example, the Fourth Amendment, ratified in 1791, does not on its face resolve whether the government may perform a search of the digital contents of a cell phone seized incident to arrest without obtaining a warrant. Thus, interpretation is necessary to determine the meaning of ambiguous provisions of the Constitution or to answer fundamental questions left unaddressed by the drafters. Some commentators have also noted the practical need for constitutional interpretation to provide principles, rules, or standards to govern future conduct of regulated parties, as well as political institutions, branches of government, and regulators. When deriving meaning from the text of the Constitution, the Supreme Court has relied on certain "methods" or "modes" of interpretation—that is, ways of figuring out a particular meaning of a provision within the Constitution. There is significant debate over which sources and methods of construction the Court should consult when interpreting the Constitution—a controversy closely related to more general disputes about whether and how the Court should exercise the power of judicial review. Judicial review at the Supreme Court, by its very nature, can involve unelected judges overturning the will of a democratically elected branch of the federal government or popularly elected state officials. Some scholars have argued that in striking down laws or actions, the Court has decided cases according to the Justices' own political preferences. In response to these concerns, constitutional scholars have constructed theories designed to ensure that the Justices following them would be able to reach principled judgments in constitutional adjudication. In 1987, Professor Richard Fallon of Harvard Law School divided "interpretivists," or those purporting to prioritize the specific text and plain language of the Constitution above all else, into two basic camps: "On one side stand 'originalists,'" whom he characterized as taking "the rigid view that only the original understanding of the language and the framers' specific intent ought to count. On the other side, 'moderate interpretivists' allow contemporary understandings and the framers' general or abstract intent to enter the constitutional calculus." Whether or not Professor Fallon's precise description at the time was accurate, those regarding themselves as originalists have clarified that the Court should rely on the fixed meaning of the Constitution as understood by at least the public at the time of the Founding. This has become known as the original public meaning of the Constitution. On the other hand, still other commentators have questioned the legitimacy of fixating on what the Framers, ratifiers, or members of their generation might have considered the core meaning of a particular provision of the Constitution, and have instead suggested interpretive methods that ensure the Court's decisions allow government to function properly, protect minority rights, and safeguard the basic structure of government from majoritarian interference. Although the debate over the proper sources of the Constitution's meaning remains unresolved, several key methods of constitutional interpretation have guided the Justices in their decisionmaking and, more broadly, have influenced constitutional dialogue. It is possible to categorize the various methods that have been employed when interpreting the Constitution. This report broadly describes the most common modes of constitutional interpretation; discusses examples of Supreme Court decisions that demonstrate the application of these methods; and provides a general overview of the various arguments in support of, and in opposition to, the use of such methods by the Court. The modes discussed in detail in this report are (1) textualism; (2) original meaning; (3) judicial precedent; (4) pragmatism; (5) moral reasoning; (6) national identity (or "ethos"); (7) structuralism; and (8) historical practices. In explaining these modes, this report is merely describing the most common methods on which the Justices (and other interpreters) have relied to argue about the meaning of the Constitution. Depending on the mode of interpretation, the Court may rely upon a variety of materials that include, among other things, the text of the Constitution; constitutional and ratification convention debates; prior Court decisions; pragmatic or moral considerations; and long-standing congressional or legislative practices. It is important to note that the Court may use more than one source in deciding a particular case, and the Justices must exercise some discretion in choosing or coordinating the sources and materials they will consult in making sense of those sources. Understanding these methods of interpretation may assist Members of Congress in observing the oath they take to uphold the Constitution when performing their legislative functions and fulfilling Congress's role as a coequal branch of government. For example, Members of Congress may interpret the Constitution when considering whether to vote for proposed legislation or when a dispute arises regarding the boundaries between Congress's own constitutional authority and that of the executive branch (e.g., a dispute over the reach of Congress's oversight power or the scope of Executive privilege). And knowledge of the most common methods for elaborating on the Constitution's meaning may aid Senators and the Senate Judiciary Committee in examining the judicial philosophy of individuals the President nominates to serve on the federal courts. It may also assist Members and congressional committees in evaluating executive branch officials' interpretations of the Constitution. Textualism is a mode of legal interpretation that focuses on the plain meaning of the text of a legal document. Textualism usually emphasizes how the terms in the Constitution would be understood by people at the time they were ratified, as well as the context in which those terms appear. Textualists usually believe there is an objective meaning of the text, and they do not typically inquire into questions regarding the intent of the drafters, adopters, or ratifiers of the Constitution and its amendments when deriving meaning from the text. They are concerned primarily with the plain, or popular, meaning of the text of the Constitution. Textualists generally are not concerned with the practical consequences of a decision; rather, they are wary of the Court acting to refine or revise constitutional texts. The Justices frequently rely on the text in conjunction with other methods of constitutional interpretation. The Court will often look to the text first before consulting other potential sources of meaning to resolve ambiguities in the text or to answer fundamental questions of constitutional law not addressed in the text. For example, in Trop v. Dulles , a plurality of the Court held that the Eighth Amendment prohibited the government from revoking the citizenship of a U.S. citizen as a punishment. When determining that a punishment that did not involve physical mistreatment violated the Constitution, the Court first looked briefly to the text of the Amendment, noting that the "exact scope" of the phrase "cruel and unusual punishment" in the Eighth Amendment had not been "detailed by [the] Court." The plurality then turned to other modes of interpretation, such as moral reasoning and historical practices, in deciding the case. The Trop plurality's use of textualism in combination with other interpretive methods is distinguishable from a stricter textualist approach espoused most famously by Justice Hugo Black. Consistent with his view that those interpreting the Constitution should look no further than the literal meaning of its words, Justice Black contended that the text of the First Amendment, which states, "Congress shall make no law . . . abridging the freedom of speech, or of the press" absolutely forbids Congress from enacting any law that would curtail these rights. An example of Justice Black's use of textualism in a First Amendment case is his dissent in Dennis v. United States . In that case, the Court held that Congress could, consistent with the First Amendment's guarantee of freedom of speech, criminalize the conspiracy to advocate the forcible overthrow of the United States government. The Court determined that the severity of potential harm to the government from the speech in question justified Congress's restrictions on First Amendment rights. In accordance with his views that the text of the Constitution should serve as the sole source of its meaning, Justice Black dissented on the grounds that the Court should not have applied a balancing test to uphold the law against First Amendment challenge. He wrote, "I cannot agree that the First Amendment permits us to sustain laws suppressing freedom of speech and press on the basis of Congress' or our own notions of mere 'reasonableness.'