U.S. ConstitutionArticle I — The Legislative BranchSubarticle 9Section 3
No Bill of Attainder or ex post facto Law shall be passed.
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