The unauthorised arrival of asylum seekers was a key political issue in the 2013 Australian federal election. On 18 September 2013, the day the new conservative government was sworn into office, a new border protection policy took effect. Termed ‘Operation Sovereign Borders’ (OSB), it is based on the premise that Australia is facing a ‘border protection crisis’ requiring a military-led response. This article begins by examining the background to OSB and what is known about its practical operation, given the lack of transparency about ‘on water’ matters, including whether boats have been intercepted or pushed back, and how such operations have been conducted. It then evaluates OSB in light of Australia’s obligations under international refugee law, international human rights law, and the law of the sea. The final section briefly contextualises these obligations domestically by examining a 2014 High Court challenge to certain aspects of OSB. The article concludes by noting that whatever attempts the government might make to quarantine domestic law and policy from Australia’s international legal obligations, this does not relieve Australia of those obligations as a matter of international law, and Australia remains liable under international law for any violations that occur.