The governance of the Australia Antarctic Territory (AAT) and Australia's broader interests in Antarctica are affected by international and domestic law. Since 1961 the Antarctic Treaty has provided the basis for a remarkable legal regime which maintains, in a unique way, equilibrium between the interests of Antarctic claimants and others. The formation of a system of international legal instruments around this treaty has transformed a continent essentially emply of regulation into a model of international cooperation and stewardship. It is within this context that Australia, as both a claimanant and an active supporter of the system, negotiates and balances its interests and frames its laws. This chapter outlines the matrix provided by the Treaty itself, in areas that are vital to Australia's policy objectives, before considering the implications for Australian sovereignty in Antarctica and the domestic legal structures that Australia has a place for the AAT.