precise so as to enable citizens to reasonably foresee the consequences of actions which trigger a withdrawal of nationality. 13 Therefore the current possibility of deprivation of citizenship based only a requirement of “conducive to the public good” would appear to confer the Secretary of State a broad, vague and subjective discretion to determine whether, when and why to deprive a person of citizenship which is contrary to the principle of legal certainty, as provided for in Article 15 ICCPR. This lack of transparency and predictability, could be interpreted as contrary to the prohibition of arbitrary deprivation of citizenship, and extends to the very qualification of a terrorismrelated offense. In an earlier communication, the Experts drew the Government’s attention to the fact that some provisions of the Counter-Terrorism and Sentencing Act (2021), in particular those qualifying terrorist offences, raised issues of incompatibility with the United Kingdom’s international obligations, as they leave much leeway for assumptions and lack precision, particularly in cases where the offences have not been fully completed (see JOL GBR 7/2020). Such vague provisions pose a fundamental challenge to the principles of legality and of certainty of the law, enshrined in article 15(1) ICCPR and article 7 ECHR and non-derogable even in times of emergency. This principle requires that criminal laws must be sufficiently precise so it is clear what types of behaviour and conduct constitute a criminal offence and what would be the consequence of committing such an offence. This principle also recognizes that illdefined and/or overly broad laws are open to arbitrary application and abuse. We remind your Excellency’s Government that the Special Rapporteur on the promotion and protection of human rights and fundamental freedoms while countering terrorism has highlighted the dangers of overly broad definitions of terrorism in domestic law that fall short of international treaty obligations. 14 Further, where States introduce new grounds for loss or deprivation of nationality, they should include transitional provisions to prevent an individual from losing their nationally due to acts or facts which would not have resulted in loss or deprivation of nationality before the introduction of a new ground. 15 States should protect against the adverse consequences of withdrawal of nationality and not artificially prolong offences or draw adverse consequences from previous acts or omissions, in line with the general principle that a person may not be tried for conduct that was not an offence at the time the conduct occurred. States should also take into consideration the time factor in carrying out a proportionality test, including the amount of time elapsed between the commission of an act or omission and the withdrawal of nationality. 16 Purpose The deprivation must serve a legitimate purpose that is consistent with international law and must be necessary and proportionate to the well-articulated interest that the State seeks to protect. 17 As set out by the International Law 13 15 16 17 UNHCR, ‘UNHCR Guidelines on Statelessness No. 5’ (May 2020), para.92. 14 A/70/371, para. 46(c)); A/73/361, para. 34. UNHCR, ‘UNHCR Guidelines on Statelessness No. 5’ (May 2020), para. 93. UNHCR, ‘UNHCR Guidelines on Statelessness No. 5’ (May 2020), para. 94. ‘Arbitrary deprivation of nationality: Report of the Secretary-General’, UN Doc. A/HRC/10/34, 26 January 2009, para. 49; ‘Human Rights and arbitrary deprivation of nationality: Report of the Secretary-General’, UN Doc. 4