nationality is an ineffective anti-terrorism measure and may even work against the goals of counter-terrorism policy.”323 192. Both the UN General Assembly and the UN Security Council have repeatedly stressed that the maintenance of fair trial and due process guarantees, as well as effective criminal justice systems, are among “the best means for effectively countering terrorism and ensuring accountability .324 The UN Security Council noted that “failure to comply with these and other international obligations [...] is one of the factors contributing to increased radicalization and fosters a sense of impunity .325 States are under an obligation to bring terrorists to justice, under the principle to extradite or prosecute (aut dedere aut judicare), as has been noted by the Security Council as well as the General Assembly on various occasions.326 This principle has been particularly important in the fight against ‘impunity’, which refers to the impossibility of bringing perpetrators of violations to account “since they are not subject to any inquiry that might lead to their being accused, arrested, tried and, if found guilty, sentenced to appropriate penalties, and to making reparations to their victims .327 The need to prevent impunity by holding perpetrators to account domestically is evidenced in the number or treaties that require a State party to ensure that prohibited acts are considered an offence and punishable under national laws.328 The UNHCR Guidelines No. 5 state that “wherever possible, the countries of nationality of individuals who become members of armed or non-State groups abroad (for example, foreign terrorist fighters) should effectively investigate and prosecute those individuals. 329 193. A violation of international law is clear whenever States, by means of depriving a person of their nationality, expel known terrorists from their territory, as they fail to punish terrorist action. However, a violation also occurs when a State expels a former national from its territory because that person is suspected of having committed terrorist acts. By depriving a person of their nationality and expelling or stranding them to a third country, a State loses effective control over that individual. This has been recognised to make it more difficult or even impossible to monitor and prosecute terrorists, which is at odds with durable, worldwide security.330 As recalled in the context of Principle 7.2, States are under the obligation to prosecute persons suspected of terrorist acts if they have jurisdiction and “the deprivation of nationality on grounds related to terrorism may not serve as a pretext for doing away with the State’s responsibility to prosecute a terrorist .331 323 CoE PACE Resolution 2263 (2019) para 8. See further also Principle 7.2. See UN Security Council Resolution 2925, pp. 1, and UNGA Res 72/180 (10 December 2017), UN Doc A/RES/72/180, pp. 2. 325 UNSC Res 2178 (24 September 2014) UN Doc S/RES/2178 (2014), pp. 1-2. 326 E.g. UN Security Council Resolutions 1456 (20 January 2003) UN Doc S/RES/1456 (2003), 1566 (8 October 2004) UN Doc S/RES/1566 (2004), 1624 (14 September 2005) UN Doc S/RES/1624 (2005), 2178 (24 September 2014) UN Doc S/RES/2178 (2014). As well as: General Assembly Resolutions 72/180 (10 December 2017), UN Doc A/RES/72/180 and 72/284 (26 June 2018) UN Doc A/RES/72/284. This is not an exhaustive list. 327 UN Commission on Human Rights, ‘Report of the independent expert to update the Set of principles to combat impunity, Diane Orentlicher. Addendum: Updated Set of principles for the protection and promotion of human rights through action to combat impunity’, E/CN.4/2005/102/Add.1 (February 2005), available at: https://undocs.org/E/CN.4/2005/102/Add.1 , pp. 6. 328 E.g. 1948 Convention on the Prevention and Punishment of the Crime of Genocide (adopted 09 December 1948, entered into force 12 January 1951) UNTS vol 78, No 1021, p. 277, art V; see also Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (adopted 10 December 1948, entered into force 26 June 1987), UNTS vol 1465, No 24841, p. 85. 329 Para 68 citing UNGA res 2625 (XXV), 24 October 1970. 330 cf CoE Committee on Legal Affairs and Human Rights AS Jur , ‘Withdrawing nationality as a measure to combat terrorism: a human rightscompatible approach? Report’, AS Jur , para . 331 Ibid, para. 4.4. 324 91