Connecticut's legislature had set aside a probate decree and ordered a new hearing, which benefited the Calders at the Bulls' expense. The losing side argued the legislative act was an ex post facto law forbidden by Article I, § 10. Justice Chase's seriatim opinion drew the line that still governs today: the Ex Post Facto Clauses of Article I reach only retroactive criminal statutes — laws that punish acts innocent when done, aggravate a crime, increase punishment, or alter evidentiary rules to a defendant's disadvantage. Retroactive civil legislation, however unjust, must be tested under other constitutional provisions (Due Process, Contracts, Takings). Calder is also famous for the Chase–Iredell exchange over whether courts may invalidate laws that violate 'natural justice' absent a written constitutional command — an early skirmish in the debate over judicial review and unenumerated rights that would echo through Lochner, Griswold, and Dobbs.