Artikel 4

1. Each State Party shall take such measures as may be necessary to establish its jurisdiction over the offences referred to in article 3, paragraph 1, when the offences are committed in its territory or on board a ship or aircraft registered in that State.
2. Each State Party may take such measures as may be necessary to establish its jurisdiction over the offences referred to in article 3, paragraph 1, in the following cases:
a) When the alleged offender is a national of that State or a person who has his habitual residence in its territory;
b) When the victim is a national of that State.
3. Each State Party shall also take such measures as may be necessary to establish its jurisdiction over the above-mentioned offences when the alleged offender is present in its territory and it does not extradite him or her to another State Party on the ground that the offence has been committed by one of its nationals.
4. This Protocol does not exclude any criminal jurisdiction exercised in accordance with internal law.