The Australian Citizenship Amendment (Allegiance to Australia) Act 2015 (Cth) (the Act) contemplates the revocation by conduct of Australian citizenship in certain circumstances. This article considers this controversial development by reference to four branches of international law. International law on nationality specifies certain preconditions before individuals can be lawfully deprived of their nationality. International law for preventing statelessness indicates that individuals cannot be rendered stateless. Under international human rights law, individuals cannot be arbitrarily deprived of or discriminated against in the enjoyment of their human right to a nationality. Any deprivation of nationality must first satisfy certain procedural requirements and substantive benchmarks. Emergent international law concerning the treatment of aliens similarly emphasizes the importance of procedural safeguards on revocation and expulsion decisions. The national law of several States is also considered. This article contends that any legislation which contemplates the revocation of Australian citizenship must demonstrate unequivocal compliance with applicable international legal standards. It concludes that, although Australian citizens can be permissibly deprived of their nationality under international law, the Act runs counter to international attempts for reducing statelessness, is not wholly compatible with human rights standards, and overlooks recent developments on the appropriate treatment of aliens.