8 Melbourne University Law Review [Vol 41(2):Adv powers to revoke citizenship in 2002, 2006 and 2014.23 On each of these three occasions, the expansions to revocation laws were introduced in the aftermath of events that heightened national security concerns: the September 11 terrorist attacks on the World Trade Centre in 2001, the 2005 London bombings, and increased foreign fighter engagement in the conflicts in Syria and Iraq from 2011 onwards.24 The UK’s 21st-century reinvigoration of the practice of disloyalty based citizenship revocation commenced in the aftermath of the 11 September 2001 terrorist attacks. In 2002, a government White Paper was published, ‘recommending that denationalization laws be “update[d]” and used to illustrate the State’s “abhorrence” of certain crimes’.25 Following this, Parliament passed legislation replacing the assortment of specific denaturalisation powers that the Home Secretary had held under the British Nationality Act 26 with a broad executive power to revoke a person’s citizenship, exercisable whenever the Secretary believed that it would be ‘seriously prejudicial to the vital interests of … the United Kingdom’ for that person to continue to hold citizenship.27 Additionally, citizenship revocation was no longer confined to naturalised citizens — the deprivation power was also exercisable against natural-born citizens.28 However, in practice only UK citizens with dual citizenship were vulnerable to denationalisation as the legislation precluded citizenship deprivation where this would result in statelessness.29 Matthew Gibney has noted that the introduction of a broad denationalisation power was tempered by the high threshold of the 23 Nationality, Immigration and Asylum Act 2002 (UK) s 4; Immigration, Asylum and Nationality Act 2006 (UK) s 56; Immigration Act 2014 (UK) s 66; Pillai and Williams (n 9) 532. 24 See generally Pillai and Williams (n 9) 532–6. 25 Ibid 532, quoting Home Office, Secure Borders, Safe Haven: Integration with Diversity in Modern Britain (Cm 5387, 2002) 35 [2.23]. 26 The grounds that gave rise to denationalisation powers in the 1981 Act related to ‘loyalty, criminality and trading with the enemy’: Gibney, ‘The Deprivation of Citizenship in the United Kingdom’ (n 12) 330; see generally at 329–30. 27 Nationality, Immigration and Asylum Act 2002 (UK) s 4(1), amending British Nationality Act 1981 (UK) s 40(2). 28 Nationality, Immigration and Asylum Act 2002 (UK) s 4(1), amending British Nationality Act 1981 (UK) s 40(1). 29 Nationality, Immigration and Asylum Act 2002 (UK) s 4(1), amending British Nationality Act 1981 (UK) s 40(4). Advance Copy