Question in Class-What If.....

Here's some info I found re: what if a law changes, and the crime you committed is no longer an offense:

ABA Family Legal GuideCriminal Justice
Court Procedures
Appeals of Criminal Cases
What if the law changes after a court convicts me?
"If a court convicted you for something that is no longer a crime, you might be able to have your conviction overturned. This also might be possible if a trial court denied you a right that the U.S. Supreme Court later rules is guaranteed by the U.S. Constitution. Your rights will depend on whether the new rule or law is retroactive, that is, applied to past court decisions. As a general rule, a change in the law would be retroactive to your criminal case if the case has been appealed but not resolved at the time the law is changed. If, on the other hand, your case on appeal has been resolved, the change in the law would not be retroactive to your case, unless the change is one that directly enhances the accurate determination of your guilt or innocence."