Due process refers to the constitutional requirement, found in the Fifth and Fourteenth Amendments to the U.S. Constitution, that government may not deprive a person of “life, liberty, or property, without due process of law.”¹⁾ The Fifth Amendment's clause restrains the federal government; the nearly identical clause in the Fourteenth Amendment restrains state governments. Courts have developed two broad branches of doctrine under this language: procedural due process, concerning the fairness of the methods government uses before depriving someone of a protected interest, and substantive due process, concerning whether certain government actions may be taken at all regardless of procedure. The existence, scope, and legitimacy of the latter branch is itself a long-running interpretive dispute; see due-process-substantive-due-process-viewpoint and due-process-substantive-due-process-debate.

Procedural due process is well established and relatively uncontroversial in its core application. Courts generally require notice and an opportunity to be heard before the state may deprive a person of a recognized life, liberty, or property interest, along with protections such as an unbiased decision-maker.²⁾ The leading modern framework for what process is “due” in a given administrative or civil context is the three-factor balancing test from *Mathews v. Eldridge* (1976), which weighs the private interest at stake, the risk of erroneous deprivation under existing procedures, and the government's interest in avoiding additional procedural safeguards.³⁾ In criminal proceedings, due process principles also underlie rules against the use of unduly prejudicial evidence, prosecutorial suppression of favorable evidence, and convictions obtained through biased tribunals.⁴⁾

Substantive due process has had a more contested trajectory. Courts have largely abandoned the Lochner-era approach, roughly 1897 to 1937, when substantive due process was used to strike down minimum wage and labor laws in the name of protecting freedom of contract. Since the mid-20th century, the doctrine has instead been the vehicle by which the Supreme Court has recognized a range of unenumerated rights said to be “deeply rooted in American history and tradition,” in areas including marriage, parenting, contraception, and other matters of personal autonomy.⁵⁾ The clause is also the textual basis for “incorporation,” the doctrine under which most provisions of the Bill of Rights are applied against state governments through the Fourteenth Amendment.⁶⁾ Separately, due process doctrine underlies the “void for vagueness” rule, under which a law may be struck down if it fails to give a person of ordinary intelligence fair notice of what conduct is prohibited.⁷⁾

A related current question is whether Fifth and Fourteenth Amendment due process must always be construed identically given their nearly identical text. In *Fuld v. Palestine Liberation Organization* (2025), the Supreme Court held that the Fifth Amendment's Due Process Clause does not limit federal courts' personal jurisdiction to the same degree that Fourteenth Amendment due process limits state courts, at least where personal jurisdiction is authorized by federal statute.⁸⁾ The full reach of that holding outside the specific jurisdictional context at issue remains to be worked out in later cases.

For a fuller account of the doctrine's historical development, including the Slaughter-House Cases, the Lochner era, and the rise of selective incorporation, see due-process-history.

• Originalist/textualist skepticism of substantive due process - holds that “due process of law” originally referred only to procedural regularity and that using the clause to protect unenumerated substantive rights lacks textual or historical grounding, amounting to judges imposing their own policy preferences. See due-process-originalist-skeptical-viewpoint.
• Living Constitution defense of substantive due process - holds that due process has long been understood, including by 19th-century jurists, to impose substantive limits on government power, and that this is necessary to protect fundamental liberties not specifically enumerated in the constitutional text. See due-process-living-constitution-viewpoint.
• Privileges or Immunities alternative - associated with scholars including Akhil Amar, this view holds that the Fourteenth Amendment's Privileges or Immunities Clause, not its Due Process Clause, was the textually intended vehicle for applying the Bill of Rights against the states, and that reliance on due process for incorporation was a historical workaround following the narrow reading given to Privileges or Immunities in the *Slaughter-House Cases*. See due-process-privileges-or-immunities-viewpoint.
• Process-only formalist view - treats the Due Process Clause as primarily a separation-of-powers provision, barring the legislature and executive from performing functions (depriving persons of life, liberty, or property) that only courts may perform, without reading any broader substantive content into the text. See due-process-process-only-formalist-viewpoint.
• Critical view of incorporation as judicial overreach - holds that no matter the doctrinal label, courts have used due process to expand judicially recognized liberties at the expense of legislative authority and federalism, echoing longstanding “legislating from the bench” critiques. See due-process-incorporation-overreach-viewpoint.

• The legitimacy and proper scope of substantive due process, including its application to abortion and other matters of personal autonomy, remains a documented and ongoing controversy with identifiable institutional and judicial stakes. See due-process-substantive-due-process-scope-controversy.
• The status of Fifth Amendment due process relative to Fourteenth Amendment due process in matters of personal jurisdiction is a live and unsettled controversy following *Fuld v. Palestine Liberation Organization* (2025). See due-process-fuld-jurisdiction-controversy.

• due-process-history
• due-process-substantive-due-process-debate
• due-process-incorporation-debate
• due-process-substantive-due-process-viewpoint
• due-process-living-constitution-viewpoint
• due-process-originalist-skeptical-viewpoint
• due-process-substantive-due-process-scope-controversy
• due-process-fuld-jurisdiction-controversy
• Fourteenth Amendment
• Fifth Amendment
• Equal Protection Clause

⁹⁾ U.S. Const. amend. V; U.S. Const. amend. XIV, § 1.

¹⁰⁾ “Due Process Generally,” Constitution Annotated, Congress.gov, Library of Congress, accessed June 26, 2026, https://constitution.congress.gov/browse/essay/amdt14-S1-3/ALDE_00013743/.

¹¹⁾ *Mathews v. Eldridge*, 424 U.S. 319 (1976).

¹²⁾ “Due Process Supreme Court Cases,” Justia U.S. Supreme Court Center, accessed June 26, 2026, https://supreme.justia.com/cases-by-topic/due-process/.

¹³⁾ “Overview of Substantive Due Process,” Constitution Annotated, Congress.gov, Library of Congress, accessed June 26, 2026, https://constitution.congress.gov/browse/essay/amdt14-S1-6-1/ALDE_00013814/.

¹⁴⁾ “Due Process Clause,” Wikipedia, accessed June 26, 2026, https://en.wikipedia.org/wiki/Due_Process_Clause.

¹⁵⁾ *Coates v. Cincinnati*, 402 U.S. 611 (1971).

¹⁶⁾ *Fuld v. Palestine Liberation Organization*, 606 U.S. ___ (2025); see also “U.S. Supreme Court Rules On Fifth Amendment Due Process Analysis For Personal Jurisdiction When Authorized By Federal Statute,” Cleary Gottlieb, July 8, 2025, https://www.clearygottlieb.com/news-and-insights/publication-listing/us-supreme-court-rules-on-fifth-amendment-due-process-analysis-for-personal-jurisdiction.