110 2. No exceptional circumstances whatsoever, whether a state of war or a threat of war, internal political instability or any other public emergency, may be invoked as a justification of torture. 3. An order from a superior officer or a public authority may not be invoked as a justification of torture. Article 3 1. No State Party shall expel, return („refouler“) or extradite a person to another State where there are substantial grounds for believing that he would be in danger of being subjected to torture. 2. For the purpose of determining whether there are such grounds, the competent authorities shall take into account all relevant considerations including, where applicable, the existence in the State concerned of a consistent pattern of gross, flagrant or mass violations of human rights. Article 4 1. Each State Party shall ensure that all acts of torture are offences under its criminal law. The same shall apply to an attempt to commit torture and to an act by any person which constitutes complicity or participation in torture. 2. Each State Party shall make these offences punishable by appropriate penalties which take into account their grave nature. 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. Article 6 1. Upon being satisfied, after an examination of information available to it, that the circumstances so warrant, any State Party in whose territory a person alleged to have committed any offence referred to in article 4 is present shall take him into custody or take other legal measures to ensure his presence. The custody and other legal measures shall be as provided in the law of that State but may be continued only for such time as is necessary to enable any criminal or extradition proceedings to be instituted.