2022 Statelessness & Citizenship Review 4(1) INTRODUCTION Armed conflicts involving non-state armed groups are creating a vast number of refugees and displaced people,1 and many of these protracted crises attract foreign fighters from all over the globe.2 States have responded to some citizens leaving their countries in order to join a terrorist or proscribed group abroad by depriving those individuals of their citizenship. Instead of repatriating their citizens or allowing them to return, governments strip them of their citizenship and thereby obstruct their journey home. Through this instrument of citizenship deprivation, states want to ensure that foreign terrorist fighters (‘FTFs’)3 are not able to carry out terrorist attacks when returning back home, as well as deter others, including naturalised citizens, from joining such groups. In addition, there have been examples of the use of deprivation of nationality as a punishment for other crimes in the UK.4 However, a number of studies have shown that in regard to terrorism cases this seems to be an unfounded security concern, as the rate of terrorist-related recidivism for those that commit acts of terrorism is relatively low when compared to other crimes.5 Although official numbers on citizenship deprivation imposed due to affiliation with terrorist groups are difficult to obtain in almost every country, it is estimated that, in recent years, more than 300 persons were deprived of their nationality in just the following seven countries: at least 209 in the UK between 2010 and 2020;6 1 2 3 4 5 6 For example, the civil war in Syria has already led to 6.6 million Syrian refugees and 6.7 million internally displaced people: see ‘Syria Emergency’, UNHCR (Web Page, 15 March 2021) <https://www.unhcr.org/uk/syria-emergency.html>. This article uses the term ‘foreign fighter’ in accordance with the following definition by the Geneva Academy of International Humanitarian Law and Human Rights: [a] foreign fighter is an individual who leaves his or her country of origin or habitual residence to join a non-State armed group in an armed conflict abroad and who is primarily motivated by ideology, religion, and/or kinship. See Geneva Academy of International Humanitarian Law and Human Rights, Foreign Fighters under International Law (Academy Briefing No 7, October 2014) 5–6 <https://www.genevaacademy.ch/joomlatools-files/docmanfiles/Publications/Academy%20Briefings/Foreign%20 Fighters_2015_WEB.pdf>. For the purpose of defining terms, we will refer to this group as foreign terrorist fighters (‘FTFs’) throughout this paper. These fighters were defined as such due to the rising phenomenon in Iraq and Syria in 2014 outlined in UN Security Council, Resolution 2178 (2014), UN Doc S/RES/2178 (24 September 2014). See, eg, Ahmed & Others (Deprivation of Citizenship) [2017] UKUT 00118 (IAC); Aziz & Others v Secretary of State for the Home Department [2018] EWCA Civ 1884. See, eg, Andrew Silke and John Morrison, ‘Re-Offending by Released Terrorist Prisoners: Separating Hype from Reality’ (Policy Brief, ICCT, September 2020) <https://icct.nl/app/ uploads/2020/09/Re-Offending-by-Released-Terrorist-Prisoners.pdf>; Thomas Renard, ‘Overblown: Exploring the Gap Between the Fear of Terrorist Recidivism and the Evidence’ (2020) 13(4) CTC Sentinel 19; Mia Bloom and John Horgan, Small Arms: Children and Terrorism (Cornell University Press 2019). Secretary of State for the Home Department (‘SSHD’), HM Government Transparency Report: Disruptive and Investigatory Powers 2015 (Report No Cm 9151, November 2015) 25; SSHD, HM Government Transparency Report: Disruptive and Investigatory Powers 2017 (Report No Cm 9420, February 2017) 26; SSHD, HM Government Transparency Report: Disruptive and Investigatory Powers 2018 (Report No Cm 9609, July 2018) 27; SSHD, HM Government Transparency Report: Disruptive Powers 2018/19 (Report No CP 212, March 2020) 22 (‘Transparency Report 2018/19’); SSHD, HM Government Transparency Report: Disruptive Powers 2020 (Report No CP 621, March 2022) 27. 34