In the context of this case, which was over a criminal matter, they cannot pass a retroactive law. ("ex post facto") For civil matters, yes, with a bunch of as

In the context of this case, which was over a criminal matter, they cannot pass a retroactive law. ("ex post facto") For civil matters, yes, with a bunch of asterisks: https://www.law.cornell.edu/constitution-conan/article-1/section-9/clause-3/ex-post-facto-laws https://www.law.cornell.edu/constitution-conan/article-1/sec...