Both the Fifth Amendment and the Fourteenth Amendment to the Constitution prohibit governmental deprivations of “life, liberty, or property, without due process of law.” The Due Process Clause of the Fourteenth Amendment serves three distinct functions in modern constitutional doctrine, in the words of the Supreme Court in 1986: “First, it incorporates [against the States] specific protections defined in the Bill of Rights . . . Second, it contains a substantive component, sometimes referred to as ‘substantive due process’ . . . Third, it is a guarantee of fair procedure, sometimes referred to as ‘procedural due process’ . . .” Daniels v. Williams (1986) (Stevens, J., concurring).

Modern law interprets the Fifth and Fourteenth Amendments to impose the same substantive due process and procedural due process requirements on the federal and state governments. The doctrine of procedural due process under both amendments, as well as the definition of “life, liberty, or property” as the range of interests protected by the respective Due Process Clauses, is addressed in more detail in the essay on Due Process in the Fifth Amendment. This essay will address substantive due process and the use of the Fourteenth Amendment’s Due Process Clause as a vehicle for incorporating selected provisions of the Bill of Rights against the states.

To understand the Fourteenth Amendment’s Due Process Clause, one must start with the Fifth Amendment’s Due Process Clause, from which the language of the Fourteenth Amendment’s provision was drawn nearly verbatim. Although the phrase “due process of law” first appeared in the fourteenth century with a very narrow and technical meaning involving the service of appropriate writs, the American Founding generation likely identified the Fifth Amendment’s Due Process Clause with the clauses, prevalent in state constitutions in 1791, that required governmental deprivations of life, liberty, or property to conform to “the law of the land,” as well as appropriate notice and ability to defend oneself in court.

There are certain respects in which “due process of law,” understood as equivalent to “the law of the land,” uncontroversially regulates the substance of governmental action. Most obviously, the core meaning of “law of the land” provisions, dating back to the Magna Carta, is to secure the principle of legality by ensuring that executive and judicial deprivations are grounded in valid legal authority. In this respect, the Fifth Amendment’s Due Process Clause limits the substance of executive or judicial action by requiring it to be grounded in law.

The term “substantive due process” as used in modern discourse conventionally does not refer to the principle of legality or limitations on Congress’s power to prescribe novel adjudicatory procedures for the deprivation of life, liberty, or property. Instead, it generally refers to limitations on the substance of legislation (other than legislation that seeks to alter the procedural aspect of “due process of law”). Few constitutional doctrines generate more heat than substantive due process. Many scholars doubt whether there is any legitimate doctrine of substantive due process, and there is a dispute among those who advocate some form of substantive due process about the scope and content of that doctrine.

Many advocates of substantive due process openly eschew any reliance on original meaning as support for their position, but some do find an originalist warrant in the doctrine. Originalist defenders of substantive due process emphasize the Due Process Clause’s links to “law of the land” provisions and the likely eighteenth-century American understanding of those provisions. Americans were familiar with, and influenced by, the writings of English judges and legal scholars such as Sir Edward Coke and Sir William Blackstone. In the seventeenth century, Coke sought to check the arbitrary rule of the Stuart monarchs by emphasizing that the “law of the land” clause in the Magna Carta encompassed both procedural safeguards and substantive limitations on the power of government; monopoly grants, according to Coke, were invalid as contrary to “the law of the land.” Scholars have debated whether Coke’s understanding of the Magna Carta was correct, but there is no doubt that his views markedly influenced constitutional development in the American colonies. Blackstone, in his widely read and influential Commentaries on the Laws of England (1765–1769), also discussed the Magna Carta’s “law of the land” provision in terms of both procedure and substance. Thus, some have argued, founding-era persons conversant with Blackstone and Coke would be disposed to a broad reading of “law of the land” provisions so as to place certain fundamental rights beyond the reach of government, and the Fifth Amendment’s Due Process Clause, and therefore the Fourteenth Amendment’s Due Process Clause, are best understood as part of this “law of the land” tradition.

Skeptics of substantive due process counter on several levels. First, they respond that British traditions of restraints on royal power do not readily translate into American constitutional restraints on congressional power. Second, they say that most of the substantive concerns voiced by pre-1791 writers are addressed by provisions written into the Constitution rather than the Due Process Clause, such as the Fifth Amendment’s Takings Clause and the original Constitution’s Ex Post Facto, Bill of Attainder, and Necessary and Proper Clauses. The skeptics maintain that there is no reason to force those substantive concerns into the unpromising language of “due process of law.” Third, they argue that attempts to draw too close a linkage between the Due Process Clause and broadly and substantively construed “law of the land” provisions run headlong into the Supremacy Clause, which declares that all valid congressional statutes are, in fact, the “supreme Law of the Land.” On balance, say the critics of substantive due process, the phrase “due process of law” is best read as compelling the government to act according to traditional modes of procedure (“due process”) and pursuant to valid legal authorization (“of law”).

The scope of the Due Process Clause was not a serious topic of discussion in the decades immediately after the Founding. The Supreme Court did not decide a case squarely involving the Fifth Amendment due process guarantee until the infamous Dred Scott v. Sandford decision in 1857. Even so, the use of the Due Process Clause in that case was brief and cryptic: the Court said only that a statute that effectively frees any slave brought by his or her master into federal territory “could hardly be dignified with the name of due process of law.”

State courts in the pre–Civil War era dealt more actively with issues of due process. Some courts equated due process with procedural requirements only, whereas others in the antebellum era wrestled with substantive interpretations of due process. State courts early established the principle that transfer of property from one person to another by legislative fiat violated due process. Further, in the landmark case of Wynehamer v. People (1856), the New York Court of Appeals struck down a prohibition statute as applied to the sale of liquor owned when the law became effective. Holding that the act constituted a deprivation of property without due process, the Wynehamer court anticipated later doctrinal development by invalidating a generally applicable regulation on due process grounds. Thomas M. Cooley, in his influential work, A Treatise on the Constitutional Limitations Which Rest Upon the Legislative Power of the States of the American Union (1868), insisted that due process was not satisfied merely by any duly enacted legislation.

Rather, he argued that due process was not simply procedural but limited the legislature from violating fundamental constitutional values.

In 1868, the Fourteenth Amendment was added to the Constitution, and since that time, historians have debated what the intentions of the framers and ratifiers of the amendment were. Clearly the amendment was designed to extend protection to the newly freed slaves against mistreatment by the states. Some thought that the Bill of Rights’ guarantees would now limit the states through the Privileges or Immunities Clause. A few, like Justice Joseph P. Bradley, thought that whatever “due process of law” meant in 1791, by 1868 it clearly signaled substantive restraints on legislation. Yet others no doubt believed that the Fourteenth Amendment’s Due Process Clause had precisely the same meaning as the Fifth Amendment’s Due Process Clause, so that if there was no legitimate doctrine of substantive due process under the latter, there could not be any such doctrine under the former either.

The Supreme Court at first construed narrowly the due process requirement of the Fourteenth Amendment. It adhered to the view that the Bill of Rights was not extended to the states by virtue of that amendment. It further held that the Due Process Clauses in the Fifth and Fourteenth Amendments had the same meaning, so that substantive due process under the two provisions had to stand or fall together. Disagreeing with the majority, Justice John M. Harlan argued that the Due Process Clause of the Fourteenth Amendment created a national standard of rights. And Justice Stephen J. Field forcefully maintained that the Due Process Clause protected the right to pursue lawful trades and contractual freedom from abridgement by the states. Field’s understanding of the Fourteenth Amendment gained ground on the Supreme Court in the late nineteenth century.

Under Chief Justice Melville W. Fuller, the Court relied on substantive due process to uphold a variety of economic rights. In a line of cases, the Court held that under due process, regulated industries were entitled to charge reasonable rates. The justices ruled in Allgeyer v. Louisiana (1897) that the right to make contracts was a liberty interest protected by the Due Process Clause, thereby establishing the liberty of contract doctrine. In the seminal case of Lochner v. New York (1905), the Court invoked due process to strike down a state law regulating the hours of work in bakeries as an interference with contractual freedom. Building on the liberty of contract principle, the Court later determined in Adkins v. Children’s Hospital of D.C. (1923) that a minimum wage law for women violated due process. The Court also relied on substantive due process to safeguard other types of fundamental rights not enumerated in the Constitution. For example, Pierce v. Society of Sisters (1925) affirmed the right of parents to control the education of their children.

The political triumph of the New Deal and the resulting constitutional revolution of 1937 transformed the interpretation of the Due Process Clause. The Supreme Court signaled its rejection of substantive due process as a basis on which to review economic legislation in West Coast Hotel Co. v. Parrish (1937). Until this point state and federal courts had not carefully differentiated between the procedural and substantive components of due process. As the unitary understanding of due process shattered, judges began in the 1940s to employ the term “substantive due process” for the first time.

The Court further downplayed the rights of property owners in United States v. Carolene Products Co. (1938) by holding that economic regulations would not be found to violate the Due Process Clause so long as they satisfied a minimal “rational basis” test. Conversely, the Court indicated that other rights deemed fundamental would receive heightened scrutiny. It is difficult to reconcile Carolene Products with the language of the Due Process Clause, which draws no distinction between the right to property and other personal rights, especially because the Framers of the Constitution and Bill of Rights closely identified security of private property with political freedom. The opinion also ranked rights into categories not expressed in the Constitution. Nonetheless, Carolene Products virtually eliminated due process review of economic regulations. In any event, scholars and justices steeped in Progressive–New Deal jurisprudence exaggerated the impact of the earlier substantive due process decisions and pictured these cases as examples of unwarranted judicial policy-making. After the mid-1930s, the Supreme Court did not invalidate a regulatory statute on grounds of due process until BMW of North America, Inc. v. Gore (1996), which concluded that there was a due process right not to be charged excessive punitive damages. Scholars debate whether the decision is grounded in substantive due process or in the procedural due process principle requiring one to be given fair notice of possible punishment.

Recent scholarship among originalists has sought to rehabilitate the bona fides of the Lochner line of cases, noting, for example, that the so-called substantive due process cases sought only to protect property owners from arbirtrary deprivations by applying the traditional due process principle of legality.

More controversial has been the Supreme Court’s revival of substantive due process to safe-guard noneconomic rights that are not set out in the written text of the Constitution. Some modern critics, such as Robert H. Bork, have insisted that due process pertains entirely to matters of procedure, and the Court has gone beyond its function in finding that due process protects certain substantive liberties. Justice Antonin Scalia, in particular, has criticized the inconsistent picking among rights to receive substantive due process protection. In the discovery of new liberties protected by due process, the Court has more recently left behind both the text of the Constitution and historical tradition. These substantive personal rights include the right to marry and a right of privacy that encompasses the right of married couples to use birth-control devices. In Roe v. Wade (1973) the Court extended the concept of privacy to cover the right to obtain an abortion. In Planned Parenthood of Southeastern Pennsylvania v. Casey (1992), the Court grounded the abortion right in a highly subjective theory of the individual, extending, some observers believe, the principle to protect private homosexual acts in Lawrence v. Texas (2003). In striking down part of the federal Defense of Marriage Act that had denied federal benefits to “married” same-sex couples, the Court seemed to extend the principle from Lawrence. Justice Anthony Kennedy declared that the federal law violated “basic due process . . . principles” in that it was “motivated by an improper animus” against homosexual persons lawfully married under state law. United States v. Windsor (2013). On the other hand, earlier in Washington v. Glucksberg (1997), the justices held that the Due Process Clause does not encompass an asserted individual liberty to commit an assisted suicide.

Until the ratification of the Fourteenth Amendment, the accepted opinion was that the Bill of Rights restricted only the federal government, a principle affirmed in Barron v. City of Baltimore (1833). Some abolitionists thought otherwise, and some think that the Privileges or Immunities Clause of the Fourteenth Amendment was meant to undo Barron and apply the Bill of Rights protections (and perhaps others in the Constitution) to the states. In The Slaughter-House Cases (1873), the Supreme Court sheared the Privileges or Immunities Clause of any real strength. If there were to be any application to the states of the guarantees found within the Bill of Rights, it would have to come through some other route.

At first, the Court did not “incorporate” rights within the Bill of Rights into the Fourteenth Amendment. Rather, the Court determined that the same right that was protected by the Bill of Rights against federal infringement was also protected against state infringement by the Due Process Clause of the Fourteenth Amendment. Later, Justice Felix Frankfurter would state that the clause had an “independent potency” separate from that of the Bill of Rights.

In Chicago, Burlington & Quincey Railroad Co. v. Chicago (1897), the justices unanimously determined that the Due Process Clause required the states to provide just compensation when they acquired private property for public use. Thus, the just compensation principle of the Fifth Amendment became in effect the first provision of the Bill of Rights to be federalized. In Gitlow v. New York (1925), the Court similarly suggested that principles of free speech basically identical to those contained in the First Amendment applied to the states by virtue of the Fourteenth Amendment. From the 1940s onward, however, the view that the Fourteenth Amendment’s Due Process Clause literally “incorporates” the text of various provisions of the Bill of Rights rapidly gained steam. By the 1960s, what we know today as the “incorporation doctrine” was complete. Under current law, most provisions of the Bill of Rights are deemed applicable to the states in precisely the same manner that they are applicable to the federal government. Notable exceptions to the rule of incorporation are the Fifth Amendment’s requirement of indictment by grand jury, the Seventh Amendment’s guarantee of jury trial in civil cases, and, perhaps, the Third Amendment. (Similarly, ever since Bolling v. Sharpe in 1954, the Fifth Amendment’s Due Process Clause has been held to “reverse-incorporate” the Fourteenth Amendment’s Equal Protection Clause against the federal government.)

The incorporation doctrine, although settled as law, remains controversial in a number of respects. During the doctrine’s formative years in the mid-twentieth century, Justice Hugo L. Black consistently maintained that all of the provisions in the first eight amendments should be deemed incorporated against the states, not simply those that the Court considers to be sufficiently fundamental. Adamson v. California (1947). Justice Frankfurter, as noted above, believed that the fundamental rights protected by the Due Process Clause were independent of those in the Bill of Rights, though they may coincide in some instances. The route the Court chose was “selective incorporation,” often attributed to Justice Benjamin N. Cardozo’s opinion in Palko v. Connecticut (1937). Through selective incorporation, the Warren Court brought most of the Bill of Rights into the Fourteenth Amendment, though the selective incorporation doctrine did not restrain some justices from finding additional rights to add that were not in the Bill of Rights.

More recently, in McDonald v. City of Chicago (2010), a plurality of the Supreme Court concluded that the Due Process Clause of the Fourteenth Amendment made the Second Amendment right to keep and bear arms applicable to the states. It reasoned that self-defense was a fundamental right entitled to substantive protection. Justice Clarence Thomas, concurring, favored overruling Slaughter-House and insisted that the right to bear arms is a privilege of citizenship protected under the Privileges or Immunities Clause.