The Oceans as a Commons: everyone’s, no-one’s, or a public good?

Douglas Guilfoyle

Are the oceans a commons? The high seas are open to all nations and governed by international law, reflecting Grotius’s mare liberum principle of unhindered access for trade, fishing, and navigation. Historically, the high seas were minimally regulated, with law focusing on flag-state jurisdiction and rules of naval warfare. The 1982 UN Convention on the Law of the Sea (UNCLOS) marked a pivotal moment, introducing Global South-led ideas of national Exclusive Economic Zones, shared responsibility for high seas fisheries, and the reservation of the high seas for peaceful purposes. Critically, it introduced a regime for seabed mining and equitable benefit-sharing but left marine biodiversity conservation in areas beyond national jurisdiction largely unaddressed. Recent efforts, like the 2023 High Seas Biodiversity Treaty, aim to fill this gap. Ultimately, the high seas are a global public good requiring shared responsibility and stewardship. Its legal regime is dynamic, and has shown the capacity to evolve to address new challenges and promote collective governance for sustainable use and protection.

Professor Douglas Guilfoyle joined UNSW Canberra in 2018, specializing in maritime security, international law of the sea, and international and transnational criminal law. His research focuses on maritime law enforcement, naval warfare, international tribunals, and the history of international law. A 2022–2025 ARC Future Fellow, he investigates small states’ litigation against greater powers. He is also a non-resident fellow at the Sea Power Centre – Australia, and was a Visiting Legal Fellow at DFAT (2018–2019). Previously, he served as a law professor at Monash University and a Reader at UCL, and has practised and advised government and international organisations.