§ 1
No punishment without law
2) A penalty more severe than the penalty provided for at the time of the commission of the act may not be imposed. A preventive measure may be ordered only if such preventive measure or a punishment or preventive measure comparable in nature was provided for at the time of the commission of the act. In the event that a preventive measure that is merely comparable in nature is imposed, the perpetrator may not be subject to less favourable treatment than was permissible under the law in force at the time of the act.
§ 61
Temporal application
The criminal laws shall be applied to acts committed after their entry into force. They shall be applied to acts committed earlier if the laws in force at the time of the act, in their overall effect, were not more favourable to the perpetrator.
2. If a State becomes a Party to this Statute after its entry into force, the Court may exercise its jurisdiction only with respect to crimes committed after the entry into force of this Statute for that State, unless that State has made a declaration under article 12, paragraph 3.
1. No person shall be criminally responsible under this Statute for conduct prior to the entry into force of the Statute.
2. In the event of a change in the law applicable to a given case prior to a final judgement, the law more favourable to the person being investigated, prosecuted or convicted shall apply.