Suppose a new law was passed in a US state banning jaywalking, which was not previously illegal in this state. (That's just a random example; the particular offense is not relevant.)

It is common for laws to increase penalties for repeated violations. For example, this jaywalking law might specify a $50 fine for a first offense, $100 for a second, $150 for a third, and $300 for a fourth or greater violation.

Suppose, however, that it also specifies that if the government can prove that the person did what is now illegal jaywalking before the law was passed, each incident that can be proved counts as a past violation for the purposes of the law. For example, if someone is caught jaywalking for the first time under this law, but the government can also prove that they jaywalked legally twice before the law took effect, this is considered a third offense and leads to a $150 fine.

Is this an unconstitutional ex post facto law?


1 Answer 1


Is this an unconstitutional ex post facto law?

Yes. Past actions were lawful, and they can’t be made unlawful simply because there is irrefutable evidence that they happened.

I think you’d actually face the same problem with actions for which the statue of limitations has expired. You can’t punish them today for acts which it is unlawful to punish them for today.

The closest you could probably get is a maximum sentence taking their history and likelihood of repeating into consideration. That isn’t punishing them for past actions, it is treating them with a reasonable appreciation of their chance of recidivism and/or threat to the community.

Also see Beazell v. Ohio: where the court says

It is settled, by decisions of this Court so well known that their citation may be dispensed with, that any statute which punishes as a crime an act previously committed which was innocent when done, which makes more burdensome the punishment for a crime after its commission, or which deprives one charged with crime of any defense available according to law at the time when the act was committed, is prohibited as ex post facto

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    The hypothetical law does not criminalize past actions: it merely establishes different penalties for different people. Basing the distinction on (past) legal behavior might make it unconstitutional under the equal protection clause, but that does not seem obvious to me. For instance, I would imagine a law forbidding alcoholics from receiving liver transplantations would pass muster under the EQC, even though being an alcoholic is legal.
    – KFK
    Commented Dec 29, 2022 at 16:25

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