Ex Post Facto Definition and Legal Meaning
On this page, you'll find the legal definition and meaning of Ex Post Facto, written in plain English, along with examples of how it is used.
What is Ex Post Facto?
adj. Latin for “after the fact,” which refers to laws adopted after an act is committed making it illegal although it was legal when done, or increasing the penalty for a crime after it is committed. Such laws are specifically prohibited by the U.S. Constitution, Article I, Section 9. Therefore, if a state legislature or Congress enacts new rules of proof or longer sentences, those new rules or sentences do not apply to crimes committed before the new law was adopted.
History and Meaning of Ex Post Facto
Ex post facto is a Latin term that literally means "from a thing done afterward." In legal terms, ex post facto refers to a law or regulation that retroactively changes the legal consequences or status of an action that was performed before the enactment of that law or regulation.
The framers of the United States Constitution were concerned that lawmakers might abuse their power by passing laws that retroactively changed the status quo, punishing citizens for legal actions committed before the law was passed. Consequently, they included a clause in the Constitution, Article I, Section 9, that prohibited Congress and state legislatures from passing ex post facto laws.
Examples of Ex Post Facto
An example of an ex post facto law would be if a state passed a law declaring it illegal to own certain species of fish in private aquariums, and then punished people for owning fish they legally owned before the law's enactment. The state could not retroactively criminalize an activity that was previously legal.
Another example would be if a state increased the penalty for drunk driving, and then punished people with the new penalty for actions they committed before the enactment of that law. The new law applies only to future events, not past events.
A third example of ex post facto would be if a state changed the qualifications for a license required for a particular profession, and then disqualified people who had previously met the old qualifications. In such a case, it would be unfair to retroactively change the qualifications for people who met the previous requirements.
Legal Terms Similar to Ex Post Facto
- Due Process: Due process refers to the concept that the government must operate within the law and provide fair treatment to all citizens. It includes the prohibition of ex post facto laws.
- Double Jeopardy: Double jeopardy prohibits the government from prosecuting an individual twice for the same offense.
- Bill of Attainder: A bill of attainder is a law that punishes an individual or group without a trial. Like ex post facto laws, bills of attainder are prohibited by the U.S. Constitution.