BOOK I
GENERAL PROVISIONS
TITLE I
THE CRIMINAL LAW
CHAPTER II
OF THE OPERATIVE PERIOD OF A CRIMINAL LAW
ARTICLE 112-1
Conduct is punishable only where it constituted a criminal offence at the time when it took place.
Only those penalties legally applicable at the same date may be imposed.
However, new provisions are applicable to offences committed before their coming into force and which have not led to a res judicata conviction, when they are less severe than the previous provisions.
Non-retroactivity
Nullum crimen sine lege
EDIT.