CHAPTER II
FUNDAMENTAL RIGHTS AND FREEDOMS
59. Retrospective legislation
(a) No person shall be found guilty of any act or omission which did not constitute an offence
under Islamic Shari’ah or law at the time committed. Nor shall a more severe penalty be imposed than the one applicable at the time the offence was committed. If the punishment for an offence has been reduced between the time of commission and the time of sentencing, the accused is entitled to the benefit of the lesser punishment.
(b) This Article shall not prejudice the trial and punishment of any person for any act which was criminal according to international law.
Non-retroactivity
Nullum crimen sine lege
Nulla poena sine lege
EDIT.