U.S. Constitution, Article I — The Legislative Branch, Section 9, Clause 3
No Bill of Attainder or ex post facto Law shall be passed.
Notes
Bars the passing of any bill of attainder or ex post facto law. The prohibition applies to legislation that punishes a named person or group without a trial, and to laws that make past conduct punishable or increase the punishment for conduct that already occurred.
Use as reference
Lexinter.net | U.S. Const. art. I, § 9, cl. 3 | https://laws.lexinter.net/constitution/us/article-1/section-9/clause-3