ex post facto clause
- It's a provision found in Article I, Section 9 of the U.S. Constitution that prevents Congress from imposing retrospective laws
- The legislation was declared unconstitutional due to the ex post facto clause which prohibits the passage of retrospective laws.
- Since the ex post facto clause disallowed the creation of retroactive laws, the legislation was deemed unconstitutional.
- The lawmaker was against the new bill on the grounds it violated the ex post facto clause of the Constitution.