1. No one can be condemned for an action or an omission  which, at the time it was committed, did not constitute an offense under national or international law. Similarly, no penalty is imposed greater than that which was applicable at the time the offense was committed.

2. This article shall not affect the judgment and  punishment of a person guilty of an act or omission which, at the time when it was committed, was criminal according to the general principles of law recognized by civilized nations.