From the Court to Treaty Negotiations: How the ICJ Ruling Could Strengthen the Global Plastics Treaty

Published August 6, 2025

By Andrés Del Castillo, Senior Attorney, Helionor de Anzizu, Senior Attorney, Joie Chowdhury, Senior Attorney, Dharmesh Shah, Consulting Senior Campaigner (Plastics Treaty), and Cate Bonacini, Senior Communications Campaign Specialist at the Center for International Environmental Law, Semee Rhee, Global Policy Advisor, Break Free from Plastic, and with the support of Alexandra Harrington, Chair, IUCN WCEL Agreement on Plastic Pollution Task Force 

When the International Court of Justice (ICJ) issued its landmark climate ruling in July, it did not just reaffirm that States have a binding legal duty to prevent climate harm and protect human rights from the impacts of climate change. The opinion also represents a major milestone for climate action — it gives governments new legal leverage to address one of today’s fastest-growing environmental threats: the full life cycle of plastics. 

Now, as UN Member States gather in Geneva, Switzerland for the resumed fifth session of the intergovernmental negotiating committee to advance a plastics treaty (INC-5.2), attention is turning to how this recent ICJ ruling can — and should — inspire greater ambition and accountability in crafting the world’s first treaty to tackle plastic pollution across its entire life cycle.

The ICJ ruling followed an extraordinary collaborative effort by youth campaigners from the Pacific and beyond, Vanuatu, the Pacific Islands, and climate-affected nations demanding legal clarity on States’ climate obligations. While the ruling made headlines around the world, a key question remains: What influence does an Advisory Opinion actually have?

As delegates convene for the first environmental treaty negotiation since the ICJ Advisory Opinion was issued, negotiators and observers alike are asking how this historic legal precedent could help shape — and strengthen — the path toward a legally binding agreement on plastic pollution.

The Influence of Advisory Opinions on Negotiating Fora

One doesn’t need to look long or hard to find examples of ICJ opinions that went on to influence treaty negotiations. There are examples of ICJ Advisory Opinions that were issued before or during treaty negotiations and went on to influence those processes. The 1996 ICJ Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons was issued almost a decade before the Treaty on the Prohibition of Nuclear Weapons. In that Advisory Opinion, two key factors emerged: 

1. A need to clarify legal aspects that the Court did not fully resolve, especially the use of nuclear weapons under all circumstances. 
2. A powerful dissenting opinion from Judge Christopher Gregory Weeramantry asserted the illegality of nuclear weapons under international law.

Together, these pieces helped shape the discourse around the need for a treaty, contributing to the momentum pushing for negotiations and eventually, the treaty’s content. 

The Fossil Fuel-Plastics Connection

During the first round of the Plastics Treaty negotiations, the UN Secretary-General set the tone by affirming, in political terms, what science has long made clear and what countries need to confront head-on within the negotiations: “Plastics are fossil fuels in another form.” Indeed, 99 percent of plastics are made from fossil fuels, the leading cause of climate change and the dominant source of global greenhouse gas (GHG) emissions. It has been clear from the beginning that to address the main drivers of plastic pollution, countries need to cut plastic production. 

It is possible to contextualize arguments from the ICJ Advisory Opinion and apply them to the Plastics Treaty space when it comes to existing obligations. Some experts have already started to do that, and in the days that followed the Advisory Opinion, over 47 UN independent human rights experts wrote to urge countries to implement the Advisory Opinion during INC-5.2. 

There is a wealth of evidence linking climate change and plastics. A recent inventory showed more than 6,400 peer-reviewed scientific articles on topics ranging from plastics and emissions to carbon sequestration and the Earth’s radiation budget. One study demonstrates that under a business-as-usual scenario, plastic production could account for up to 31 percent of the global carbon budget by 2050.

When the ICJ Advisory Opinion clearly states that “… failure of a State to take appropriate action to protect the climate system from GHG emissions — including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies — may constitute an internationally wrongful act attributable to that State,” it strengthens the legal basis for ambitious States to argue that unchecked plastic production is incompatible with international climate obligations. This explicit recognition of the need to address emissions from both plastic production and plastic consumption provides a strong legal foundation for countries to pursue both approaches within the framework of the Plastics Treaty.

Paving the Way for the Plastics Treaty

Since the Plastics Treaty negotiations began in 2022, a string of decisions from major international courts and tribunals has laid the foundation for States taking ambitious action against plastic pollution. 

In 2024, the International Tribunal of the Law of the Sea (ITLOS) issued an Advisory Opinion on Climate Change. The Advisory Opinion makes the argument that anthropogenic GHG emissions fall within the scope of “pollution of the marine environment” as defined under the United Nations Convention on the Law of the Sea (UNCLOS) and that States must take all necessary measures to prevent, reduce, and control marine pollution by anthropogenic GHG emissions. The Tribunal further specified that the current international climate legal regime is applicable but not exclusive in establishing States’ legal duties in relation to climate change. Other sources of international law are also relevant and applicable. 

The ITLOS Advisory Opinion also acknowledges that while the current climate treaty regime is significant, it is insufficient to fully meet the climate-relevant obligations set out under UNCLOS, such as the obligations to protect and preserve the marine environment, as well as to prevent, reduce, and control pollution of the marine environment (UNCLOS Arts 192 and 194). 

Earlier this year, the Inter-American Court of Human Rights issued an Advisory Opinion on Climate Emergency and Human Rights. It emphasizes that customary international law remains central to the context, notably through obligations to prevent transboundary harm and to engage in good faith in international cooperation. The duty to cooperate should occur through financial means, technology transfer, capacity building, and the establishment of international forums and the formulation of collaborative international policies.

The ICJ Advisory Opinion builds upon both of these opinions by addressing a number of issues that are also applicable to plastics, in particular, plastic production and plastic-related GHG emissions, while leaving some issues unresolved and requiring States to negotiate appropriate solutions. 

Given the far-reaching recognition of the right to a clean, healthy, and sustainable environment (R2HE) in national, regional, and international instruments, the Court critically recognized the right as a binding norm of international law and a precondition for the enjoyment of many other human rights. In other words, States cannot claim compliance with human rights treaties unless they also ensure environmental protection. 

The ICJ climate ruling also affirmed the long-recognized right to health (para. 379). It further underscored the urgent need for States to take binding action against climate change, including regulating private emissions, and specifically highlighted that the conduct that leads to emissions, such as production or granting licenses or subsidies for fossil fuels production and consumption, may constitute an internationally wrongful act. This may include plastic production, the expansion of plastic production capacity, and related licenses — across the full life cycle, including the production of primary, secondary, and final manufactured plastic — and subsidies.

Recognizing the Root: Fossil Fuels and the Climate Crisis

While science has consistently pointed out that fossil fuels are the root cause of climate change, climate treaties (e.g., the United Nations Framework Convention on Climate Change [UNFCCC], the Paris Agreement, the Kyoto Protocol, and the Kigali Amendment to the Montreal Protocol) have remained silent about them. This outcome reflects the influence of fossil fuel-producing States and their interests during the negotiation process. Since then, Parties have been working to right this wrong to ensure a coherent and global approach to fossil fuels. In the case of the UNFCCC, it took decades for the Conference of the Parties to explicitly mention fossil fuels. 

Addressing plastic production is as mission-critical to the Plastics Treaty as mentioning fossil fuels is to climate treaties. Member States must not repeat the missteps of past agreements by omitting the root causes of the plastics crisis from the treaty’s scope and ambition. 

Developing a Plastics Treaty with the ICJ Advisory Opinion in Mind

While the 140-page ruling touches on many themes, six are especially pertinent to the Plastics Treaty and that Member States should consider when negotiating it. 

1. The Duty to Prevent Harm

The ICJ affirmed that States have a binding legal duty to prevent climate harm. We know that 80 percent of the GHG emissions across the life cycle of plastics happen during production. Therefore, for countries to avoid legal responsibility for conduct that contributes to carbon emissions, they need to implement the ICJ’s ruling by addressing both plastic production and consumption. 

Heading into INC-5.2, the working text (the Revised Chair’s Text) lacks any direct reference to the climate system or GHG, despite the urgent need to explicitly address climate issues, including emissions, within the future treaty. When developing a target for reducing plastic production, it will be essential to include one that reduces virgin plastic production in line with the climate goal of 1.5°C, as both science and law require. 

2. Scientific Attribution

The ruling also endorses the use of scientific attribution and harm/injury as intertwined elements, underscoring that science is essential in establishing damage in the context of climate change. 

The same logic applies to the harms caused by plastic pollution. There is a growing body of scientific evidence linking micro- and nanoplastics, chemicals of concern, emissions, and releases to impacts on health — including, but not limited to, cancer and endocrine disruption, biodiversity loss, and climate change. 

3. Legal Attribution

GHG emissions, such as plastic pollution, are a transboundary problem that often involves multiple States. Here, the ruling states, “the rules on State responsibility are capable of addressing situations where damage is caused by multiple States engaging in wrongful conduct, and that the responsibility of a single State for damage may be invoked without invoking the responsibility of all States that may be responsible.” (para. 430) Under this rule, a single State, among multiple States and actors causing harm, can still be held liable for breaching its obligation and for contributing to the collective injury caused. 

This ruling is particularly significant for transboundary environmental concerns such as plastic pollution that involve multiple States causing global environmental harm, where shrouded obligations and evaded responsibilities make it difficult to attribute harm. However, with this ruling, the Court further emphasizes the general law of State responsibility and therefore provides a clearer legal pathway to hold States to account. 

4. Private Actors

Regarding private actors, the Court has highlighted that States must regulate private emissions. States are under a legal duty to regulate GHG emissions — including from private companies and investors from all sectors, notably the petrochemical sector: “[a] State may be responsible where, for example, it has failed to exercise due diligence by not taking the necessary regulatory and legislative measures to limit the quantity of emissions caused by private actors under its jurisdiction.” (para. 428). This ruling will undoubtedly have an impact on corporate actors in the petrochemical industry, as petrochemicals are derived from fossil fuels. 

Crucially, even where a State has previously granted licenses or otherwise failed to act, the legal obligation to reduce emissions and transition away from fossil fuels persists: “The breach by a State of its international obligations does not extinguish its underlying duty of performance.” (para. 446).

5. Concrete Targets and Measures

To meet obligations under international law, including the climate and human rights regimes, as well as under UNCLOS, it is essential for States to adopt concrete measures and objectives. In the context of global targets, the ICJ affirmed that the 1.5°C target is the primary temperature goal agreed by Parties under Article 2 of the Paris Agreement, recognizing it as the benchmark for limiting global warming. It stressed the urgency of action, the gap between current commitments and the 1.5°C goal, and the duty of States to act with due diligence to meet this target. 

Concrete targets and measures established under the Plastics Treaty would not only fulfill these obligations but also provide the necessary legal framework and clarity — especially for the private sector — in our interconnected world. 

Furthermore, a global primary plastic production target would help define and quantify States’ obligations under UNFCCC and UNCLOS, while ideally aligning with the Paris Agreement’s temperature goal. To implement it effectively, countries would need to adopt national targets that contribute to a global cap, allowing for a degree of flexibility based on national circumstances.

6. Reparation

One of the ruling’s clearest affirmations is that historical emissions matter, and those suffering from the impacts of climate devastation have a right to remedy and reparation. Many of the communities most impacted by climate change live in countries that bear less historical responsibility for GHG emissions. When considering remedies or reparations, it is essential to look at those countries that are the highest historical emitters. 

Redress under the law of State responsibility entails halting harmful conduct, giving assurances of non-repetition, and providing full reparation, including restitution or restoring the situation prior to the violation of international law; financial compensation as relevant; and satisfaction, which may take the form of formal apologies or education of society about climate change. Because climate obligations are owed to all other States (“erga omnes partes”), any State may demand cessation, guarantees, or reparation, even if it is not directly injured.

Again, there is considerable thematic overlap with plastic pollution. Ninety percent of all the plastic that was ever made still exists. This legacy plastic is a major problem that Member States must contend with in the treaty. Like with GHG emissions, some countries bear more historic responsibility than others. To address this, the Plastics Treaty will need a dedicated article that addresses historic plastic pollution. AOSIS and other countries have also expressed the desire to establish a dedicated fund or subfund to support remediation efforts. 

Conclusion

The ICJ ruling delivers a clear, courageous, and unambiguous opinion on a politically sensitive issue. As the first-ever mandate to craft a legally-binding instrument that addresses the full life cycle of plastic, the upcoming Plastics Treaty negotiations are a critical test of how the ruling will be used in practice. But the opinion will not be enough. 

So far, the Plastics Treaty negotiations have relied on consensus decision-making, allowing any one country veto power. With Member States that have a vested interest in continuing petrochemical production in the room, consensus necessitates lowering decisions to the lowest common denominator. Reaching for a Plastics Treaty that is in line with the ruling will require States to rise above obstructionism and deploy all of the tools that multilateralism offers, including voting. Doing so will require legal clarity and political courage — just as the Court has demonstrated.