''Chapter II: Fundamental Rights and Freedoms, Article 33: The Principle of Legality and Proportionality in Criminal Cases''
4. Punishments shall be administered in accordance with the law in force at the time a criminal act was committed, unless the penalties in a subsequent applicable law are more favorable to the perpetrator.
Article 2 Principle of legality
2. No criminal sanction or measure of mandatory treatment may be imposed on a person for an act, if prior to the commission of the act, the law did not define the act as a criminal offense and did not provide a criminal sanction or measure of mandatory treatment for the act.
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.