An action that criminalizes an act after it occurs is a(n)
A. ex post facto law
B. bill of attainder
C. habeas corpus law
D. exclusionary rule type of law
E. reaction to shifts in societal morality
Option A is the only possible answer to this question. The phrase ex post facto is Latin for “from a thing done afterward.” In other words, it is from a law that is made after an act has already been done. An ex post facto law is one that makes a behavior criminal (and allows you to be punished for it) even though the behavior was legal when you engaged in it.
All of the other answers are clearly wrong. A bill of attainder is a law passed by a legislature declaring someone guilty of some crime and mandating that they be punished. Habeas corpus law requires that the government give a legal reason to hold someone in jail. It prevents a person from being held in prison without being charged with a crime. The Exclusionary Rule says that evidence that the government gets illegally cannot be used in court. Option E is simply a way in which we can describe some Supreme Court decisions, such as Roe v. Wade or the recent decision that there is a constitutional right to same-sex marriage.
Thus, Option A is clearly the only possible answer.