Article I, Section 9, Clause 3:

No Bill of Attainder or ex post facto Law shall be passed.

Since the 1798 case Calder v. Bull, the Supreme Court has interpreted the Ex Post Facto Clauses to apply only to laws that are criminal or penal in nature, not to civil laws.1 The Court has explained, however, that “the ex post facto effect of a law cannot be evaded by giving a civil form to that which is essentially criminal.” 2 In Calder, 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.3

Supreme Court decisions from the nineteenth century suggested that a legislature might violate the Ex Post Facto Clauses in ways that do not fit within any of the four categories recognized in Calder.4 However, in the 1990 case Collins v. Youngblood, the Court rejected that reasoning and held that the scope of the prohibition on ex post facto laws is “defined by the Calder categories.” 5

Footnotes

1

Calder v. Bull, 3 U.S. 386, 389 (1798); see also, e.g., Watson v. Mercer, 33 U.S. 88, 110 (1834) ( “The constitution of the United States does not prohibit the states from passing retrospective laws generally; but only ex post facto laws. Now it has been solemnly settled by this court, that the phrase, ex post facto laws, is not applicable to civil laws, but to penal and criminal laws.” ). For additional discussion of certain categories of laws that have generally been held to be non-penal in nature, see ArtI.S9.C3.3.10 Retroactive Taxes and Ex Post Facto Laws and ArtI.S9.C3.3.12 Ex Post Facto Laws, Deportation, and Related Issues. For discussion of other constitutional provisions that apply exclusively to penal laws, see ArtI.S9.C3.1 Historical Background on Bills of Attainder, ArtI.S10.C1.4 State Bills of Attainder, and Amdt5.3.1 Overview of Double Jeopardy Clause.

2

Burgess v. Salmon, 97 U.S. 381, 385 (1878); see also Cummings v. Missouri, 71 U.S. 277, 278 (1866).

3

Calder, 3 U.S. at 390. Cf. Trop v. Dulles 356 U.S. 86, 95 (1958) ( “In deciding whether or not a law is penal, this Court has generally based its determination upon the purpose of the statute. If the statute imposes a disability for the purposes of punishment—that is, to reprimand the wrongdoer, to deter others, etc., it has been considered penal. But a statute has been considered nonpenal if it imposes a disability, not to punish, but to accomplish some other legitimate governmental purpose. The Court has recognized that any statute decreeing some adversity as a consequence of certain conduct may have both a penal and a nonpenal effect.” ) (footnotes omitted).

4

Kring v. Missouri, 107 U.S. 221, 228 (1883), overruled by Collins v. Youngblood, 497 U.S. 37 (1990); cf. Thompson v. Utah, 170 U.S. 343, 352 (1898) (same).

5

497 U.S. 37, 47 (1990).