Abstract
Marine protected areas (MPAs) are a fundamental tool for effective marine conservation and areas beyond national jurisdiction (ABNJ) prove most challenging for their designation. Largely to blame is the currently fragmented and sector-based governance framework under the United Nations Convention on the Law of the Sea (UNCLOS, 1982). In the face of rapidly deteriorating biodiversity in ABNJ, negotiations are underway for a new international legally binding instrument (ILBI) mandated to promote the conservation and sustainable use of biodiversity beyond national jurisdiction using tools including MPAs. The Southern Ocean, however, is a uniquely governed space, with two MPAs already established in ABNJ under the Antarctic Treaty System (ATS). This article critically examines the status quo for designating MPAs under the ATS and uses the findings to reflect on how the system might interact with the new United Nations ILBI. Despite this critique, complementary synergies between the two instruments are still possible. I therefore hypothesise that Antarctic Treaty Consultative Parties (ATCPs) and members of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) must collectively engage with the ILBI process and across instruments within the ATS, to ensure the future interplay is one of opportunity, not conflict. The article concludes with recommendations to help ATCPs and CCAMLR members more proactively and effectively engage with progressions in the international law of the sea.