 A number of liberal democracies have responded to the upsurge of terrorist acts by introducing legislation that gives the state the power to withdraw the citizenship of those convicted or suspected of terrorist  activities.[14]  Given the principle recognized in international law that no one should be left stateless, these legislations usually apply only to citizens holding dual or multiple citizenships. Denationalisation is sometimes described in this context as “extending the functionality of immigration law in counter-terrorism” (Macklin 2015, see also Barry and Ferracioli 2016). Though states cannot deport their own citizens, denationalisation allows them to first withdraw citizenship and then deport. These legislations raise a number of normative issues. Firstly, they seem to contradict the basic idea that citizenship is a right, not a privilege (Gibney 2013, Macklin 2015). Secondly, since they weaken the security normally attached to the status of citizen, they can be described as demoting citizenship “to another category of permanent residence” (Macklin 2015). Thirdly, it is argued that by targeting only dual (or multiple) citizens, the new legislations treat them as second-class citizens (Gibney 2013, 653). In contrast, other theorists insist that that the particular nature of terrorist crimes (akin to acts of war against the state) warrants this kind of response (Schuck 2015; Joppke 2015). Concerning the worry that the legislations discriminate against dual citizens, the response is that the difference in treatment between mono-citizens and dual citizens is justified, since the consequences of denationalisation are also very different in each case. Individuals holding a single citizenship are the only ones facing statelessness as a consequence of denationalisation (Barry and Ferracioli 2016). Where participants in the debate find common ground is in their shared criticism of the specific form that some legislations have taken, most notably the 2006 British Nationality, Immigration and Asylum Act. In the wake of the 7 July 2005 Tube bombing in London, the new Act relaxed the standard for deprivation present in the 2002 legislation (the “vital interests of the state”test) with a much weaker and vague standard: that the individual’s holding citizenship is “not conducive to the public good” (quoted by Gibney 2013, 650). Whether this, or any such measure, has any significant deterrent effect is very much open to question. 