OFFENCES WITHIN CANADA
4.
Definitions
(3) The definitions in this subsection apply in this section.
"crime against humanity" « crime contre l'humanité »
"crime against humanity" means murder, extermination, enslavement, deportation,
imprisonment, torture, sexual violence, persecution or any other inhumane act or
omission that is committed against any civilian population or any identifiable group
and that, at the time and in the place of its commission, constitutes a crime against
humanity according to customary international law or conventional international
law or by virtue of its being criminal according to the general principles of law
recognized by the community of nations, whether or not it constitutes a
contravention of the law in force at the time and in the place of its commission.
"genocide" « génocide »
"genocide" means an act or omission committed with intent to destroy, in whole or in
part, an identifiable group of persons, as such, that, at the time and in the place of
its commission, constitutes genocide according to customary international law or
conventional international law or by virtue of its being criminal according to the
general principles of law recognized by the community of nations, whether or not it
constitutes a contravention of the law in force at the time and in the place of its
commission.
"war crime" « crime de guerre »
"war crime" means an act or omission committed during an armed conflict that, at the
time and in the place of its commission, constitutes a war crime according to
customary international law or conventional international law applicable to armed
conflicts, whether or not it constitutes a contravention of the law in force at the time
and in the place of its commission.

OFFENCES OUTSIDE CANADA
7.
Application before coming into force
*(5) Where an act or omission constituting an offence under this section occurred
before the coming into force of this section, subparagraphs (1)(a)(ii) and (2)(a)(ii) apply
to the extent that, at the time and in the place of the act or omission, the act or
omission constituted a contravention of customary international law or conventional
international law or was criminal according to the general principles of law recognized
by the community of nations, whether or not it constituted a contravention of the law in
force at the time and in the place of its commission.
*[Note: Section 7 in force October 23, 2000, see SI/2000-95.]

Crimes Against Humanity and War Crimes Act 2000

6 (5) For greater certainty, the offence of crime against humanity was part of customary international law or was criminal according to the general principles of law recognized by the community of nations before the coming into force of either of the following:

(a) the Agreement for the prosecution and punishment of the major war criminals of the European Axis, signed at London on August 8, 1945; and

(b) the Proclamation by the Supreme Commander for the Allied Powers, dated January 19, 1946.

Crimes Against Humanity and War Crimes Act 2000

7 (5) Where an act or omission constituting an offence under this section occurred before the coming into force of this section, subparagraphs (1)(a)(ii) and (2)(a)(ii) apply to the extent that, at the time and in the place of the act or omission, the act or omission constituted a contravention of customary international law or conventional international law or was criminal according to the general principles of law recognized by the community of nations, whether or not it constituted a contravention of the law in force at the time and in the place of its commission.

Crimes Against Humanity and War Crimes Act 2000

10. Proceedings for an offence alleged to have been committed before thecoming into force of this section shall be conducted in accordance with the laws of evidence and procedure in force at the time of the proceedings.

Article 11
Jurisdiction ratione temporis
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.

Article 24
Non-retroactivity ratione personae
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.