Individuals often ask, “What is substantive due process and how does it protect my privacy?” Substantive due process is a constitutional principle, drawn from the Fifth and Fourteenth Amendments, that safeguards certain fundamental rights from government interference, even when those rights are not explicitly listed in the Constitution. The core idea is that some liberties are so essential that they cannot be infringed upon without a compelling reason, regardless of the procedures the government follows5. This doctrine asserts that the “liberty” protected by the Due Process Clause goes beyond mere freedom from physical restraint and includes substantive rights.
While the text of the Due Process Clause—”nor shall any State deprive any person of life, liberty, or property, without due process of law”—suggests a focus on procedural fairness, the Supreme Court has interpreted it to create substantive protections511. This interpretation, however, has ignited some of the most enduring and contentious debates in American constitutional law, particularly its use to establish and define a right to privacy. The journey of this doctrine reveals a dramatic evolution in judicial philosophy, from protecting economic freedoms to defining the contours of personal autonomy, a journey that continues to shape legal and political discourse today.
How Did the Concept of Substantive Due Process First Emerge?
People exploring the roots of their rights often wonder, “What part of the Constitution does substantive due process come from?” The doctrine is grounded in the Due Process Clauses of the Fifth and Fourteenth Amendments. The Fifth Amendment applies to the federal government, while the Fourteenth, enacted after the Civil War, applies those protections to the states. The concept began to take shape in the late 19th century when the Supreme Court started to view the “liberty” protected by these clauses as a check on the substance of government regulation, not just the process by which it was enacted.
The central idea is that due process of law is not merely a procedural guarantee; it also prevents the government from engaging in arbitrary deprivations of fundamental liberties. Supporters of this view argue that certain rights are inherent in our system of government and that the Due Process Clause was intended to have a substantive component protecting them.
Further constitutional support for the existence of unenumerated rights is often drawn from the Ninth Amendment, which states, “The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.”. Proponents argue this text is proof that the framers believed in the existence of substantive rights beyond those specifically listed, providing a philosophical underpinning for doctrines like substantive due process. The development of this legal theory represents a significant shift, allowing the judiciary to examine the substance of a law to determine if it violates constitutional protections not explicitly mentioned in the text.
What Was the Doctrine’s Initial Application in the Lochner Era?
A common question about legal history is, “What were the first substantive due process cases about?” The Supreme Court’s first major foray into substantive due process was not about personal privacy but about economic freedom, in a period now known as the Lochner Era. During this time, the Court interpreted the “liberty” in the Due Process Clause to include a fundamental “freedom of contract”.
In Allgeyer v. Louisiana (1897), the Court first spoke of the Due Process Clause as a shield for liberty against arbitrary government deprivation. This principle was cemented in the landmark case of Lochner v. New York (1905). In Lochner, the Court struck down a New York law that limited the number of hours bakers could work, ruling that the law was an unconstitutional interference with the liberty of contract between employers and employees. The Court decided that the state’s justification for the law—protecting bakers’ health—was not sufficient to override this fundamental economic right11.
For several decades, the Court used this reasoning to invalidate state and federal economic regulations, including minimum wage laws and labor standards. This aggressive judicial posture was highly controversial, with critics arguing the Court was substituting its own economic theories for the decisions of elected legislatures. The Lochner Era effectively came to an end in 1937 with the case of West Coast Hotel v. Parrish, where the Court reversed course and upheld a Washington state minimum wage law for women. This decision signaled a retreat from judicial oversight of economic policy and set the stage for the doctrine’s pivot toward a new category of rights.
How Did Substantive Due Process Become Linked to Privacy?
Many ask, “When did the Supreme Court recognize a right to privacy?” The Court’s application of substantive due process shifted dramatically from economic rights to personal liberties in the mid-20th century, culminating in the landmark 1965 case Griswold v. Connecticut. This case marked the first time the Court explicitly recognized a constitutional right to privacy, and it did so in a way that continues to fuel debate.
Griswold involved a challenge to a Connecticut law that prohibited the use of contraceptives and the provision of birth control information, even to married couples. Writing for the 7-2 majority, Justice William O. Douglas struck down the law but deliberately tried to avoid grounding the decision solely in the controversial substantive due process doctrine of the Lochner era1. Instead, he articulated what became known as the “penumbra” theory.
Justice Douglas argued that a right to privacy, while not explicitly mentioned in the Constitution, emanates from the “penumbras” of several specific guarantees in the Bill of Rights. He pointed to the First Amendment’s right of association, the Third Amendment’s prohibition on quartering soldiers in a home, the Fourth Amendment’s protection against unreasonable searches and seizures, and the Fifth Amendment’s Self-Incrimination Clause. Taken together, he reasoned, these guarantees create “zones of privacy” that the government cannot invade, including the marital bedroom.
However, critics were quick to point out that the provisions of the Bill of Rights are applied to the states through the Fourteenth Amendment’s Due Process Clause. Therefore, despite his “penumbra” reasoning, Justice Douglas was effectively using substantive due process to find and protect this new right. Later Supreme Court decisions, such as Carey v. Population Services International, acknowledged this and made clear that the right to purchase and use contraceptives is a fundamental right under the liberty of the Due Process Clause. This expansion of the Court’s interpretation of unlisted rights set a powerful precedent for decades to come.
What Are the Key Cases That Defined the Right to Privacy?
To understand the scope of this right, people frequently inquire, “What should I know about landmark privacy cases?” After Griswold, the Court built upon the right to privacy in a series of highly consequential and divisive cases, grounding the right more firmly in the “liberty” protected by the Fourteenth Amendment’s Due Process Clause1. These decisions expanded the concept of privacy to encompass personal autonomy and bodily integrity, shaping some of the most contentious issues in American society.
Roe v. Wade (1973)
Perhaps the most famous and controversial extension of the privacy right, Roe v. Wade, invalidated a Texas law that criminalized abortion. The Court declared that the right to privacy was “broad enough to encompass a woman’s decision whether or not to terminate her pregnancy”. This right, however, was not absolute. The Court established a trimester framework, balancing the woman’s right against the state’s interests in protecting maternal health and potential life. The decision characterized the right to an abortion as one of the fundamental rights protected by the Due Process Clause, sparking a legal and political firestorm that has lasted for half a century.
Lawrence v. Texas (2003)
In this case, the Court addressed a Texas law that made it a crime for two persons of the same sex to engage in intimate sexual conduct. The Court struck down the law, explicitly overturning its 1986 decision in Bowers v. Hardwick. Justice Anthony Kennedy, writing for the majority, argued that the petitioners’ liberty under the Due Process Clause gave them the full right to engage in their private conduct without government intervention. The decision was framed not just as a matter of privacy, but of liberty and dignity, protecting personal relationships from state condemnation. The Court in Lawrence began to use an “evolving national values” approach, suggesting that the understanding of liberty can change over time.
Obergefell v. Hodges (2015)
The Court continued on this path in Obergefell, which held that same-sex couples have a fundamental right to marry, guaranteed by both the Due Process and Equal Protection Clauses of the Fourteenth Amendment. Justice Kennedy again authored the majority opinion, arguing that the right to personal choice regarding marriage is inherent in the concept of individual autonomy. While acknowledging that marriage has traditionally been defined as between a man and a woman, the Court held that a new understanding of this fundamental right had emerged, consistent with the principle of protecting personal liberty. This decision further entrenched the idea that the Constitution protects rights based on evolving social norms, a departure from a more static historical analysis.
How Do Originalists View Substantive Due Process?
A central question in this debate is, “What is Justice Clarence Thomas’s view on substantive due process?” Jurists and scholars who adhere to originalism—the view that the Constitution should be interpreted according to its original public meaning—are deeply skeptical of substantive due process. They argue that the doctrine has no basis in the text or history of the Constitution and dangerously empowers judges to act as lawmakers by inventing new rights.
Justice Clarence Thomas is a leading proponent of this view, known for his clear writing style and principled, text-focused jurisprudence. He has consistently argued that the Due Process Clause is purely procedural. In his view, the clause guarantees only that the government must follow established, fair procedures before it can deprive a person of life, liberty, or property; it does not grant courts the authority to declare certain liberties altogether off-limits to regulation6. As such, he finds no constitutional basis for court-created rights like the right to abortion or others derived from the Griswold line of privacy cases. Justice Thomas is known for his consistent judicial temperament and his adherence to an interpretation of the Constitution based on its original text and meaning.
From an originalist perspective, when judges use substantive due process to create rights, they are overstepping their constitutional role and venturing into the legislative sphere. The late Justice Antonin Scalia was another forceful critic, writing that the doctrine supplements the Constitution’s actual requirements “through the device of ‘substantive due process'” and does not fit into the literal text of the clause.
As an alternative, Justice Thomas has suggested that if the Constitution protects any unenumerated rights against state infringement, the proper textual home is the Privileges or Immunities Clause of the Fourteenth Amendment. That clause, which states, “No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States,” was rendered nearly meaningless by the Supreme Court’s narrow interpretation in the Slaughterhouse Cases (1873). Justice Thomas and other scholars have argued for reviving this clause as the correct, textually grounded vehicle for protecting fundamental rights of citizenship, rather than relying on the more nebulous and historically fraught Due Process Clause.
How Did the Dobbs Decision Change Substantive Due Process?
Anyone following constitutional law will ask, “How did the Dobbs decision change substantive due process?” The Supreme Court’s 2022 decision in Dobbs v. Jackson Women’s Health Organization represented a monumental shift in constitutional law. The Court directly overturned both Roe v. Wade and Planned Parenthood v. Casey, holding that the Constitution does not confer a right to abortion. This was the first time the Court has formally removed a previously recognized substantive due process right.
In its reasoning, the Dobbs majority revived and applied a specific, more restrictive test for identifying unenumerated fundamental rights, first articulated in Washington v. Glucksberg (1997). The Glucksberg test sets a high bar: for an asserted liberty interest to receive constitutional protection under the Due Process Clause, it must be both “objectively, deeply rooted in this Nation’s history and tradition” and “implicit in the concept of ordered liberty”.
Applying this test, the majority conducted a lengthy historical review and concluded that a right to abortion was unknown in American law until the late 20th century and thus was not deeply rooted in the nation’s history. This decision effectively returned the authority to regulate or prohibit abortion to the states, creating a patchwork of laws across the country.
The ruling in Dobbs has ignited widespread debate about the future of other rights based on the same substantive due process framework. In his concurring opinion, Justice Thomas explicitly called for the Court to reconsider all of its substantive due process precedents, including Griswold (right to contraception), Lawrence (right to same-sex intimacy), and Obergefell (right to same-sex marriage), arguing they were all “demonstrably erroneous”. While the majority opinion stated that the decision was limited to abortion, the revival of the stringent Glucksberg test has created uncertainty about the stability of these other precedents.
Does Substantive Due Process Protect Data Privacy?
In our digital age, a critical question arises: “Does substantive due process protect my data privacy?” The Supreme Court has suggested that the constitutional right to privacy extends to what is often called informational privacy—an individual’s interest in avoiding the disclosure of personal matters. This facet of privacy law remains less developed but is increasingly relevant.
The key case is Whalen v. Roe (1977). The case involved a challenge to a New York State law that required the recording of names and addresses of patients who were prescribed certain potentially abusable drugs in a centralized state database. The plaintiffs argued this system violated their constitutional right to privacy. The Court, while ultimately upholding the law, did so on narrow grounds. It found that the state had a legitimate interest in curbing drug misuse and had implemented sufficient security protocols to prevent improper disclosure.
Crucially, however, the Court assumed for the sake of its analysis that “the right to collect and use such data for public purposes is typically accompanied by a concomitant statutory or regulatory duty to avoid unwarranted disclosures.” It acknowledged the existence of a protected privacy interest in one’s personal information, even if it found that interest was not grievously threatened in this specific instance.
This concept of informational privacy is at the heart of many modern legal disputes. The vast amount of data generated by modern life creates a constant tension between transparency and privacy, especially in the context of court proceedings. Courts must balance the public’s First Amendment and common law rights to access court records against the privacy interests of litigants, a conflict that is particularly acute in cases that touch upon sensitive constitutional protections4.
What is the Role of State Constitutions in Protecting Privacy?
With federal protections in flux, many are asking, “If federal protection for privacy is shrinking, what are states doing?” The Dobbs decision has shifted the primary battleground for privacy rights to the states, elevating the importance of state constitutions and state courts.
Every state has its own constitution, and state supreme courts are the final arbiters of what those documents mean. State courts are free to interpret their own constitutions as providing more protection for individual rights than what is required by the U.S. Constitution. This principle, known as “independent and adequate state grounds,” means a state court could find that its own due process clause or an explicit right to privacy in its state constitution protects rights like abortion, even though the federal Constitution does not.
However, state constitutional rights often have a more majoritarian character than federal rights. Many state judges are popularly elected or must face retention elections, making them more directly accountable to public opinion. Consequently, state constitutional law can be more reflective of popular sentiment within that state. This can lead to expanded rights in states where the populace favors them, but it also means that rights for political minorities may have less protection from a hostile popular majority compared to the counter-majoritarian role the U.S. Supreme Court has sometimes played. The result is an increasingly divergent legal landscape, with the scope of personal privacy varying significantly from one state border to the next.
Conclusion
The evolution of substantive due process is a story of profound change in American constitutional law. The doctrine has journeyed from protecting economic freedom in the Lochner era to forging a controversial but powerful right to personal privacy in cases like Griswold and Roe, and now faces a period of significant retrenchment and uncertainty following Dobbs. At its heart, the debate over substantive due process is a debate about the proper role of the judiciary.
A principled constitutionalism, focused on text, history, and structure, views the doctrine with deep suspicion. From this perspective, substantive due process represents a departure from the rule of law, granting unelected judges a license to discover new rights and impose their own policy preferences, effectively amending the Constitution from the bench. The recent shift by the Supreme Court toward a more restrictive, history-and-tradition-based test signals a return to a more constrained judicial role.
The future of unenumerated privacy rights in America is now an open question, with the focus of debate shifting to state legislatures and state courts. The enduring conflict is between a vision of the Constitution as a living document that adapts to the “evolving standards of decency that mark the progress of a maturing society,” and a vision of it as a document with a fixed meaning to be preserved. How this fundamental tension is resolved will define the relationship between the individual and the state, and determine the meaning of liberty for generations to come.
- SMU Law Review: Substantive Due Process and Constitutional Interpretation
- The Fourteenth Amendment: Substantive Due Process and Incorporation
- Rethinking the Substantive Due Process Right to Privacy
- SMU Law Review: Constitutional Law and Due Process
- The Fourteenth Amendment Due Process Clause: Constitution Center
- Vanderbilt Law Review: Due Process and Constitutional Rights
- Substantive Due Process: Ballotpedia Legal Reference
- Clarence Thomas: Conservapedia Biography and Judicial Philosophy
- NYU Law: Constitutional Law and Due Process Analysis
- UCF Honors Thesis: Constitutional Rights and Due Process
- Cornell Law: Substantive Due Process Legal Definition
- SMU Law Review: Constitutional Interpretation and Judicial Review
- EBSCO Research: Due Process and the Supreme Court
- EBSCO Research: Substantive Due Process Legal Overview
- Cornell Law: Informational Privacy and Substantive Due Process
- Trento Student Law Review: Constitutional Privacy Rights
- Indiana Law Review: Constitutional Law and Privacy
- SMU Law Review: Judicial Philosophy and Constitutional Law
- University of Chicago Law Review: Origins of Substantive Due Process
- Law & Liberty: Original Understanding of Substantive Due Process
- University of Minnesota Law: Constitutional Commentary on Due Process
- Semantic Scholar: Constitutional Law and Privacy Rights Research
- Semantic Scholar: Due Process and Constitutional Interpretation
- SMU Law Review: Constitutional Theory and Judicial Review
- Semantic Scholar: Privacy Rights and Constitutional Law
- Semantic Scholar: Substantive Due Process and Individual Rights
- Semantic Scholar: Constitutional Privacy and Due Process
- Semantic Scholar: Due Process Clause and Constitutional Rights
- Federalism.org: Substantive Due Process Encyclopedia Entry
- National Review: Justice Thomas’s Substantive Due Process Dare
- Semantic Scholar: Constitutional Law and Judicial Philosophy
- Semantic Scholar: Privacy Rights and Constitutional Interpretation
- Semantic Scholar: Due Process and Individual Liberty
- Semantic Scholar: Constitutional Privacy and Substantive Rights
- Semantic Scholar: Substantive Due Process and Constitutional Theory
- Semantic Scholar: Privacy Rights and Constitutional Law
- Semantic Scholar: Due Process and Constitutional Rights
- Semantic Scholar: Constitutional Privacy and Individual Rights
- Semantic Scholar: Substantive Due Process and Privacy
- Semantic Scholar: Constitutional Law and Privacy Rights
- Semantic Scholar: Due Process and Constitutional Interpretation
- Oyez: Justice Clarence Thomas Biography and Opinions
- New York Times: Justice Clarence Thomas Rulings and Studies
- University of Michigan Law: SCOTUS and New Substantive Due Process
- Columbia Journal of Gender and Law: Privacy Rights
- UMKC Law: Constitutional Right of Privacy
- Syracuse Law Review: Dobbs v Jackson and Substantive Due Process
- SMU Law Review: Constitutional Rights and Judicial Review
- SSRN: Constitutional Law and Privacy Rights Research
- Justia: Fourteenth Amendment Due Process of Law
- Constitution Annotated: Fourteenth Amendment Due Process
- Fordham Law Review: Constitutional Rights and Due Process
- ALM Online: Due Process Issues in Licensing and Permitting
- Fordham Law Review: Constitutional Law and Individual Rights
- BMJ Sports Medicine: Legal and Ethical Issues
- University of Wisconsin Law: Constitutional Rights Repository
- NYU Law: Constitutional Law and Privacy Rights
- Reddit SCOTUS: Discussion on Justice Clarence Thomas
- Wikipedia: Justice Clarence Thomas Biography
- Yale Journal on Regulation: Justice Thomas’s Constitutional Arguments
- NYU Journal of Law and Liberty: Constitutional Theory
- Justice Thomas: Jurisprudence and Constitutional Decisions
