What is the test for an ex post-prosecutions clause in the Criminal Code when a defendant is charged with a crime committed before the crime was committed?

In Collins v. Youngblood (1990) 497 U.S. 37, 42, 110 S.Ct. 2715, 2719, 111 L.Ed.2d 30, the court said " 'any statute which punishes as a crime an act previously committed, which was innocent when done; which makes more burdensome the punishment for a crime, after its commission, or which deprives one charged with crime of any defense available according to law at the time when the act was committed, is prohibited as ex post facto.' [Citation.]"