The Australian migration zone is a legal device created by the Australian government for the purpose of Australia's visa policy and immigration policy, as the territory in which Australia’s visa policy applies. The Australian migration zone covers such Australian controlled territories as the government may determine. Prior to 2001, the Australian migration zone consisted of the mainland, and some external territories. Norfolk Island, for example, was not part of the Australian migration zone until 2016. Under Australia’s universal visa policy, a non-citizen must hold an Australian visa within the Australian migration zone. Without such a visa, or a bridging visa, the non-citizen is an unlawful non-citizen and treated as an “unauthorised arrival". However, the main impact of the migration