Environmental Damage at High Seas: Who Is Liable When No One Owns the Ocean?
Introduction
In 2025, a multitude of scientific data showed that deep-sea mining tests released clouds of silt and heavy metals. They stay suspended in the sea and can travel thousands of miles and choke deep coral reefs, the filters of the ocean. The question of who is liable has troubled states for decades, and more crucially, who is entitled to compensation? Neighbouring nations may come to mind, but the damage often spreads over thousands of miles and has consequential effects over time. Theoretically, it can be said that such an act causes harm to the entire human population.
However, this is not that simple. The high seas are considered a global commons, owned by no one. Complex jurisdictions make it challenging to assign legal liability even when there is clear actual harm. Additionally, to what extent should the wrongdoer be expected to pay?
High Seas and Territorial Sea
The territorial sea is considered to be 12 nautical miles from the land of a nation. This is treated as an extension of the land, and the nation exercises both sovereign and economic rights over it. The Exclusive Economic Zone of a nation extends from 12 to 200 nautical miles, and the nation enjoys economic rights in this area. Any damage caused in these zones is considered a direct loss to the nation’s economic interest, and the nation may seek recovery of the loss, rightfully.
The problem of accountability arises when damage is done to the high seas, which are defined as waters beyond 200 nautical miles of a state, as per Article 86 of the United Nations Convention on the Law of the Sea (UNCLOS). This region is freely accessible and usable by all, so it is not owned by anyone. It is hard to assign legal damage caused by any action in this region. The accused may rely on the doctrine of “Damnum Sine Injuria” to argue that, since there is no legal injury, there can be no remedy, even if harm has occurred.
Laws, national and international, also struggle with multiple complex challenges when environmental damage is caused to the high seas. It is difficult to cover all the challenges in one article, so for simplicity, we will classify the challenges into two broad, fundamental sections: Who is liable? And who should be compensated? However, first, we should examine the frameworks that govern the high seas.
Laws Governing the High Seas
At first glance, the high seas may appear to exist in a legal vacuum. Since no state owns them, it is often assumed that there are no effective laws regulating conduct in this region. This assumption, however, is only partially true. International law does recognise the need to regulate activities on the high seas, including those that cause environmental harm.
The primary legal framework governing the high seas is the United Nations Convention on the Law of the Sea (UNCLOS). Beyond regulating maritime boundaries and navigation, UNCLOS places obligations on states to protect and preserve the marine environment. States are required to ensure that activities under their control do not cause environmental damage beyond their jurisdiction.
In recent years, attempts have also been made to address gaps in this framework. The Agreement on Biodiversity Beyond National Jurisdiction, commonly referred to as the High Seas Treaty, reflects a growing recognition that existing rules are insufficient to address modern environmental threats. While the treaty strengthens environmental commitments, its enforcement still depends largely on state cooperation and domestic implementation.
Taken together, these frameworks establish that the high seas are not lawless. However, they also reveal a structural limitation: international law relies primarily on states to regulate their own actors, and there is no central authority to consistently enforce compliance. As a result, even where environmental obligations exist, translating them into accountability remains difficult.
Who Is Liable?
At a conceptual level, international environmental law relies heavily on the polluter pays principle. The logic is simple: the party responsible for causing environmental harm should bear the cost of preventing, mitigating, or repairing that harm. Many international environmental treaties and legal frameworks are based on this concept, and in theory, it provides a straightforward answer to the question of liability.
However, environmental damage on the high seas complicates this logic. Harm is often caused by private actors such as corporations operating vessels or conducting extraction activities far from any national territory. International law does not usually regulate these actors directly. Instead, responsibility is mediated through states. A state is expected to regulate activities carried out under its flag, jurisdiction, or effective control, and failure to do so may attract international responsibility.
Where environmental harm is caused by state-sponsored activities, the position is clearer. Under general principles of international law, states may be held responsible for wrongful acts attributable to them, including actions carried out by state agencies or authorised entities. In such cases, liability flows to the state itself, either directly or through a form of vicarious responsibility.
Despite this apparent clarity, practical challenges remain. States may lack effective control over private actors, may fail to enforce environmental standards, or may deny responsibility altogether. As a result, while international law provides a framework for identifying who should be liable, enforcing that liability in cases of high seas environmental damage remains uncertain.
Who Should Be Compensated?
Once liability is established, the next challenge is determining who should receive compensation for environmental damage on the high seas. Since no state owns this region, direct compensation to a single claimant is not always appropriate. One possible approach is the creation of representative mechanisms or trusts, similar to the International Seabed Authority, which act on behalf of the international community and manage shared interests in areas beyond national jurisdiction.
At the same time, compensation cannot be entirely abstract. Certain states may suffer more immediate and measurable harm due to environmental damage at sea, particularly coastal states whose ecosystems, fisheries, or economies are directly affected. In such cases, it is reasonable to prioritise compensation to the most affected states, with the amount calibrated to the intensity and proximity of the damage rather than distributed equally among all nations.
A further distinction must be drawn between different kinds of harm. Direct and identifiable damage, such as loss of marine resources or economic disruption, lends itself more easily to compensation. More complex are long-term and cumulative harms, including damage to marine biodiversity or the gradual release of toxins that affect ecosystems over time. While recovery for such harm is more difficult to quantify, excluding it entirely would ignore the very nature of environmental injury on the high seas.
Ultimately, the challenge lies in enforceability. Even if international law recognises who should be compensated and on what basis, the absence of strong enforcement mechanisms limits practical recovery. Nevertheless, the difficulty of enforcement should not negate the principle of compensation itself. Without some form of remedial framework, liability risks becoming symbolic rather than meaningful.
What Is at Stake?
The continued failure to address environmental damage on the high seas risks more than ecological loss. At a legal level, it threatens to erode trust between states in shared legal frameworks. International law depends on the expectation that obligations will be respected and breaches will carry consequences. When environmental harm in global commons goes largely unaddressed, compliance itself begins to appear optional.
More broadly, the governance of global commons is at stake. The high seas operate on the principle that shared spaces can be collectively regulated despite the absence of ownership. If damage in such spaces remains legally inconsequential, this model weakens. The implications extend beyond the oceans, as similar challenges arise in other commons such as outer space and the global climate system. How international law responds here may shape how it is relied upon elsewhere.
Conclusion
Environmental damage on the high seas exposes a fundamental tension in international law: harm can be widespread and real even when ownership is absent. While legal frameworks such as UNCLOS and newer agreements attempt to regulate activities in these shared spaces, enforcement remains indirect and dependent on state action. As a result, liability may exist in principle, but its practical application is often uncertain.
The difficulty, however, lies less in identifying responsibility and more in translating it into meaningful accountability and compensation. International law can hold polluters accountable, channel liability through states, and recognise collective interests, but it struggles to respond effectively to diffuse and long-term harm. This gap between legal obligation and enforcement risks reducing responsibility to a formal concept rather than a functional one.
Ultimately, the question is not whether the high seas are governed by law, but whether that law is capable of responding when harm occurs. If international law cannot adapt to protect shared spaces from environmental damage, the idea of global commons itself may weaken. Addressing this challenge is essential not only for the oceans but for the future governance of all spaces that lie beyond national borders.
