Citizenship Deprivation In The United Kingdom 167 there is no statutory definition of the new ground for deprivation, ‘conducive to the public good’. The concept itself is borrowed from immigration law where it is used in the context of the deportation of non-nationals. The power to deport non-nationals is directly related with the power of the state to regulate the entry and stay of aliens. In international law, it is generally asserted that no similar power is to be exercised over one’s own citizens, as this difference in treatment is one of the elements that distinguish citizens from aliens. There are no principles of international law that legitimize the expulsion of own nationals. Moreover, a state decision to deprive one of citizenship with the sole aim of expelling the person concerned would amount to arbitrary deprivation of citizenship, which is prohibited under international law. The fact that UK nationality legislation puts dual nationals, whose citizenship status is open to review via deprivation powers, on a par with expellable non-nationals is equally problematic in light of the liberal principle that all citizens are equal before the law, regardless of how they have acquired their citizenship.15 As a result of these changes, a person faced with a citizenship deprivation order can appeal on two grounds: he can either contest the order’s conduciveness to the public good or show that the order made him stateless. Up to now, most appeals have dealt with subsection 40(4) of BNA 1981, which prevents such an order to be made if the person becomes stateless. This choice can be explained by the lack of a statutory definition of the material scope of ‘conducive to the public good’, the low level of proof required for making such an order, and more generally, the judiciary’s reluctance to scrutinize executive measures taken on national security grounds, and even more so in terrorism cases. Since statelessness prevents the loss of British citizenship, its scope and the criteria used to determine its existence have taken central stage during appeal procedures to citizenship derivation orders. 3 Contesting Citizenship Deprivation Orders: Statelessness and the Courts Appeals brought before SIAC and the higher appeal courts have forced the judiciary to interpret the nationality laws of several states in order to assess 15 hatred which may lead to intra-community violence in the UK and advocate violence in furtherance of a particular belief. M. Gibney, ‘A Very Transcendental Power: Denaturalisation and the Liberalisation of Citizenship in the United Kingdom’ (2013) 61 Political Studies 637. tilburg law review 19 (2014) 163-170