The polar legal system can be considered as a dual legal system that consists of Antarctic law and Arctic law. To properly understand a real picture of polar law, it is necessary to examine key elements that characterise the law. This chapter seeks to clarify the concept of polar law by examining (1) the scope of polar law (spatial, material and temporal scopes), (2) the functions of polar law, (3) the structure of polar law and (4) the actors in polar law – that is, States, Indigenous Peoples, international organisations and private actors. While polar law as a burgeoning discipline is increasingly important, it encounters multiple challenges. Thus, this chapter also addresses challenges of polar law, including the impacts of Russia’s invasion of Ukraine in 2022.