That no ex post facto law, nor law impairing the obligation of contracts, or retrospective in its operation, or making any irrevocable grant of special privileges or immunities, can be enacted.
Ex post facto laws—impairment of contracts—irrevocable privileges
Mo. Const. art. I, § 13 — under Bill of Rights.
Mo. Const. art. I, § 13
Ex post facto laws—impairment of contracts—irrevocable privileges