Is a criminal or penal law ex post facto?

"[T]wo critical elements must be present for a criminal or penal law to be ex post facto: it must be retrospective, that is, it must apply to events occurring before its enactment, and it must disadvantage the offender affected by it." Weaver v. Graham, 450 U.S. 24, 29, 101 S.Ct. 960, 964, 67 L.Ed.2d 17 (1981) (footnote omitted). "The critical question is whether the law changes the legal consequences of acts completed before its effective date." Weaver, supra, 450 U.S. at 31, 101 S.Ct. at 965.