FREEDOM AND RESPONSIBILITY
Article XXVIII
(4) No one shall be held guilty of or be punished for an act which at the time when it was committed did not constitute a criminal offence under Hungarian law or, within the scope specified by an international treaty or a legal act of the European Union, under the law of another State.
Non-retroactivity
Nullum crimen sine lege
Nulla poena sine lege
EDIT.