Related Rule
Ireland
Practice Relating to Rule 157. Jurisdiction over War Crimes
Ireland’s Geneva Conventions Act (1962), as amended in 1998, provides for the punishment of grave breaches of the 1949 Geneva Conventions and of the 1977 Additional Protocol I committed by “any person, whatever his or her nationality” and “whether in or outside the State”. It further provides for jurisdiction of Irish courts over “minor breaches” of the 1949 Geneva Conventions and the 1977 Additional Protocols if committed by “any person, whatever his nationality … in the State” or by “any citizen of Ireland … outside the State”. 
Ireland, Geneva Conventions Act, 1962, as amended in 1998, Sections 3 and 4.
Ireland’s International Criminal Court Act (2006) states:
(1) An Irish national who does an act outside the State that, if done within it, would constitute an ICC offence or an offence under section 11(1) [Offences against the administration of justice] is guilty of that offence and liable to the penalty provided for it.
(2) Subsection (1) also applies in relation to a person of any other nationality who does an act outside the State that, if done within it, would constitute both—
(a) a war crime under subparagraph (a) (grave breaches of the Geneva Conventions) or (b) (other specified serious violations of the laws and customs applicable in international armed conflict) of Article 8.2 [of the 1998 ICC Statute], and
(b) an offence under section 3 (grave breaches of the Geneva Conventions and Protocol I thereto) of the Geneva Conventions Act 1962. 
Ireland, International Criminal Court Act, 2006, § 12(1) and (2).