Article 5 1. Each State Party shall take such measures as may be necessary to establish its jurisdiction over the offences referred to in article 4 in the following cases: (a) When the offences are committed in any territory under its jurisdiction or on board a ship or aircraft registered in that State; (b) When the alleged offender is a national of that State; (c) When the victim is a national of that State if that State considers it appropriate. 2. Each State Party shall likewise take such measures as may be necessary to establish its jurisdiction over such offences in cases where the alleged offender is present in any territory under its jurisdiction and it does not extradite him pursuant to article 8 to any of the States mentioned in paragraph I of this article. 3. This Convention does not exclude any criminal jurisdiction exercised in accordance with internal law. Features: Universal jurisdiction, extradition or prosecution Article 5 is a cornerstone of the Convention, as it concerns the obligation to establish jurisdiction over the crime of torture. Based upon the recognition that torture was already prohibited under international law115, the Convention was established in order to provide a system of enforcement under which the torturer can find no safe haven.116 Article 5 requires and facilitates the assertion of jurisdiction by States over acts of torture, including instances involving nonnationals in third States, when the alleged offender is present in their territories —that is, on the basis of so-called universal jurisdiction.117 The exercise of the jurisdiction is governed by Articles 6-8, as is outlined below. § 1. Article 5 §1 requires that each State Party take any necessary measures to establish jurisdiction in its national laws regarding the offence of torture, as referred to in Article 4. The State Party is subject to the obligation in Article 5 §1 if torture is committed in any territory under its jurisdiction or on board a ship118 or aircraft registered in the State in question; in its territorial sea or in the airspace above its territory119; or on installations such as oil rigs which may be outside its territorial sea. In other words, jurisdiction over the crime of torture must cover torture committed in all of the territory under the factual control of the State.120 To a limited extent it is also applicable to certain maritime areas outside the territorial sea over which a State has limited jurisdiction. If, for instance, torture is committed on an oil-rig or other installation placed on the continental shelf of a State Party, that State is required to establish jurisdiction over the offence.121 The obligation to establish jurisdiction also applies to cases where the alleged offender is a subject of the State. Thus, even where a State Party is accus- II. INDIVIDUAL ANALYSIS OF ARTICLES 1–16 OF THE CONVENTION 2. ANALYSIS OF SUBSTANTIVE PROVISIONS Interpretation 37