Article I, Section 10, Clause 1:
No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.
An ex post facto law is a law that imposes criminal liability or increases criminal punishment retroactively.1 Two separate clauses of the Constitution, Article I, Sections 9 and 10, ban enactment of ex post facto laws by the Federal Government and the states, respectively.2 The Supreme Court has cited cases interpreting the federal Ex Post Facto Clause in challenges under the state clause, and vice versa, treating the two clauses as having the same scope.3 The Court’s decisions interpreting both clauses are therefore discussed collectively in greater detail in the Article I, Section 9 essays on the federal Ex Post Facto Clause.4 In particular, those essays on federal and state ex post facto laws discuss Supreme Court jurisprudence addressing imposing or increasing punishments, procedural changes, employment qualifications, retroactive taxes, inapplicability to judicial decisions, and deportation and related issues.
The Supreme Court has interpreted the Ex Post Facto Clauses to limit only legislation that is criminal or penal in nature,5 though the Court has also made clear that “the ex post facto effect of a law cannot be evaded by giving a civil form to that which is essentially criminal.” 6 In addition, the Court has uniformly applied the prohibition on ex post facto legislation only to laws that operate retroactively.7 In the 1798 case Calder v. Bull, the Court enumerated four ways in which a legislature may violate the Ex Post Facto Clauses’ prohibition on imposing retroactive criminal liability: (1) making criminal an action taken before enactment of the law that was lawful when it was done; (2) increasing the severity of an offense after it was committed; (3) increasing the punishment for a crime after it was committed; and (4) altering the rules of evidence after an offense was committed so that it is easier to convict an offender.8 The Ex Post Facto Clauses are related to other constitutional provisions that limit retroactive government action, including the federal and state Bill of Attainder Clauses, the Contract Clause, and the Due Process Clauses.9
Multiple Supreme Court decisions have held that the Ex Post Facto Clauses apply only to federal and state legislation, not to judicial decisions.10 The state Ex Post Facto Clause also applies to state constitutional amendments. In Cummings v. Missouri, the Court considered a challenge to a post-Civil War amendment to the Missouri Constitution that required persons engaged in certain professions to swear an oath that they had never been disloyal to the United States.11 In holding that the amendment violated the state Ex Post Facto Clause, the Court looked to the Clause’s language providing that “'no State'—not no legislature of a State, but that 'no State'—should pass any ex post facto law,” and concluded that “[i]t can make no difference, therefore, whether such legislation is found in a constitution or in a law of a State; if it be within the prohibition it is void.” 12
- See, e.g., Calder v. Bull, 3 U.S. 386, 391 (1798); Locke v. New Orleans, 71 U.S. 172, 173 (1867).
- For the prohibition on federal ex post facto laws, see U.S. Const. art. I, § 10, cl. 1; see also ArtI.S9.C3.3.1 Overview of Ex Post Facto Laws.
- See, e.g., Peugh v. United States, 569 U.S. 530, 532–33 (2013) (case construing federal clause citing case construing state clause); Reetz v. Michigan, 188 U.S. 505, 510 (1903) (case construing state clause citing case construing federal clause).
- See ArtI.S9.C3.3.1 Overview of Ex Post Facto Laws.
- E.g., Calder, 3 U.S. at 389; Watson v. Mercer, 33 U.S. 88, 110 (1834); see also ArtI.S9.C3.3.4 Ex Post Facto Law Prohibition Limited to Penal Laws.
- Burgess v. Salmon, 97 U.S. 381, 385 (1878).
- E.g., Calder, 3 U.S. at 389; see also ArtI.S9.C3.3.3 Retroactivity of Ex Post Facto Laws.
- Calder, 3 U.S. at 390.
- See, e.g., Fletcher v. Peck, 10 U.S. 87, 138–39 (1810); cf. Landgraf v. USI Film Prods., 511 U.S. 244, 267 (1994) (the restrictions that the Constitution places on retroactive legislation “are of limited scope” and “[a]bsent a violation of one of those specific provisions,” when a new law makes clear that it is retroactive, the arguable “unfairness of retroactive civil legislation is not a sufficient reason for a court to fail to give [that law] its intended scope” ).
- E.g., Frank v. Magnum, 237 U.S. 309, 344–45 (1914); cf. Rogers v. Tennessee, 532 U.S. 451, 456–60 (2000) (holding that “limitations on ex post facto judicial decisionmaking are inherent in the notion of due process,” but the due process limitation on courts is not identical to the ex post facto prohibition that applies to legislation); see also ArtI.S9.C3.3.11 Ex Post Facto Prohibition and Judicial Decisions.
- 71 U.S. 277, 280–81 (1866).
- Id. at 307–08. For additional discussion of Cummings, see ArtI.S9.C3.3.9 Employment Qualifications and Ex Post Facto Laws.