This article has been updated to reflect the General Assembly vote.

On Wednesday, the United Nations General Assembly adopted a resolution asking the International Court of Justice to issue an advisory opinion on the legal obligations of nations with respect to climate change. 

The resolution—the culmination of a campaign led by the Pacific Island nation Vanuatu—asks the highest U.N. judicial authority to answer specific legal questions about governments’ obligations to protect the “climate system” for “present and future generations,” and what governments’ responsibilities are for “acts and omissions” that have caused harm to the climate, with an emphasis on harm to “particularly vulnerable” small island developing countries. 

In some low-lying island countries like the Marshall Islands and the Maldives, sea level rise caused by climate change threatens to completely or partly subsume their territories. Climate change has also caused other harmful impacts, including more frequent and intense storms—earlier this month Vanuatu was hit by back-to-back Category 4 cyclones. 

The advisory opinion sought by the resolution would represent the first time the so-called “World Court” weighs in what the legal obligations of nations are to address and prevent climate change. 

While not legally binding, International Court of Justice advisory opinions “carry great legal weight and moral authority,” and are often relied upon by litigants in national and sub-national courts, which do issue legally binding decisions. 

Depending on what the International Court of Justice would say about climate change, other judges could rely on the advisory opinion to force governments and polluting companies to reduce emissions or compensate plaintiffs for climate-related injuries.  

Until recently, how nations tackle climate change has largely been the exclusive province of political negotiations under the U.N. Framework Convention on Climate Change, which includes the annual Conference of the Parties, or COPs. That political process has allowed governments, particularly powerful nations like the United States, to maintain control over the outcome of climate discussions—and, according to some legal scholars, is why key parts of global climate accords, like the Paris Agreement, are not legally binding. 

For proponents of the International Court of Justice advisory opinion, this week’s General Assembly vote is a triumph in environmental justice. 

“We are at the cusp of a historic moment in ensuring countries’ legal climate obligations are acknowledged and upheld. And not a moment too soon,” Ralph Regenvanu, minister of climate change of Vanuatu, said.

Nicole Ponce, co-founder of the World’s Youth for Climate Justice, is one of the youth leaders who pushed small island nations’ governments to pursue an International Court of Justice advisory opinion on climate change. Ponce, who is from the Philippines, began campaigning for the advisory opinion at the age of 24. Now 29, Ponce said she’s overwhelmed at the amount of support the campaign has received at the U.N. 

“We primarily want the Court to clarify the obligations of states with regard to the rights of present and future generations,” she said.  

Opponents of putting climate questions before the International Court of Justice have argued that the court’s involvement could be counterproductive to ongoing political negotiations. They also have said that the questions put to the court could be badly worded, leading to an unhelpful—or harmful—decision in the eyes of those wishing for strong government action on climate change.

Despite those concerns, Vanuatu and a “core group” of 18 other climate-vulnerable nations secured broad support for the resolution, which was passed unanimously.

If the International Court of Justice agrees to hear the case, countries can submit briefs on the issue and the court could hold oral arguments in front of the 15-judge panel. Scientific and other expert witnesses could be called. The court usually takes several months to deliberate before issuing a decision by majority vote. All together, the process could take up to a year or longer. 

In addition to the International Court of Justice advisory opinion effort, two other international courts have been asked to weigh in on questions related to climate change in the past several months.  

On Dec. 12, 2022, a coalition of Pacific island nations known as the “Commission of Small Island States” asked the Hamburg-based International Tribunal for the Law of the Sea, or ITLOS, for a climate-related advisory opinion on the obligations of governments that are parties to the U.N. Convention on the Law of the Sea, an international treaty governing marine and maritime activities. In the ITLOS advisory opinion request, the Republic of Palau, Niue, the Republic of Vanuatu and Saint Lucia asked the tribunal to consider questions about government responsibilities to prevent and mitigate pollution of the marine environment and deleterious effects from climate change, like sea level rise and ocean acidification. 

Then on Jan. 9, the governments of Chile and Colombia requested an advisory opinion from the San José-based Inter-American Court of Human Rights about governments’ obligations for responding to climate change under various human rights’ laws. 

To help make sense of the potential effects of these advisory opinion efforts, Inside Climate News spoke with international lawyer Philippe Sands. Sands, a law professor and director of the Centre on International Courts and Tribunals at the University College London, has litigated cases before the International Court of Justice and the International Tribunal for the Law of the Sea, among other international courts. 

He co-founded the Center For International Environmental Law and represented the Alliance of Small Island States at the world’s first climate negotiations in 1992. Recently, he co-chaired a panel of experts that drafted a legal definition for the proposed international crime of ecocide and acted as counsel on behalf of Mauritius in the International Court of Justice’s advisory opinion on the Chagos Islands, which said that the islands were illegally separated from Mauritius and belong to Mauritius, not Britain.

This interview has been edited for clarity and length.

Is it a coincidence that there are three separate efforts for advisory opinions from international courts on climate change, or is something else afoot here? 

I think this is a novel development. I can’t think of another case in which you have, in effect, parallel proceedings on essentially the same set of issues before three international courts and tribunals, and all in reference to an advisory function. That in itself is interesting. 

Why is it happening? My hunch is that it’s probably not unrelated to the fact that there is a deadlock that the process of lawmaking, particularly under the UNFCCC and relevant protocols, is proceeding more slowly and ineffectively than some people would like. So, people are looking for other means to crack open the legal possibilities for more effective actions.

This of course raises some fundamental questions about the role of the international judge, and what are they to do when the legislative function grinds to a halt—when states seem unable to act effectively in the face of clear scientific evidence. 

There have been rumblings that these efforts could backfire, what are the chances of that? 

There is surely a need to proceed with care. The 1996 ICJ advisory opinion on nuclear weapons was pushed by some NGOs who hoped for a response from the International Court of Justice that said the use of nuclear weapons was unlawful in all circumstances. That is not what they got. 

In a 7-7 split vote, the court ruled, on the casting vote of the President, that there might be some circumstances in which the use of nuclear weapons could be lawful. That was surely not what the proponents of the exercise wanted. Regrettably, that issue is current today in relation to Russia and Ukraine, and many will have heard President Putin evoke the language of the court in saying Russia might be entitled to use nuclear weapons if its very survival would be at stake. That is the language of the ICJ in that opinion. So be careful what you ask for. 

In pushing for an idea before an international court, it will always be necessary to pay close regard to who are the judges who sit on the court, what their backgrounds are, and their propensities. ITLOS has 21 judges, the ICJ has 15 judges. Each will have their own background and interests, ideas about the judicial function. They will reach their own views on the aspects they wish to address. They will surely too be thinking about the well-being of the institution on which they happen to sit, and presumably inclined towards the greatest possible degree of consensus. One weakness of the nuclear weapons advisory decision was that it was a 7-7 split. The Chagos advisory opinion was—on the merits—without dissent and that has given it a greater authority and effect. 

Judges are a diverse group—nationally, legal culture, north/south, etc.—so looking for a decent consensus on a meaningful approach may be tough. When you’re trying to get as many judges on board with a particular opinion, many will wish to avoid a “lowest common denominator” type of approach. 

Should environmentalists be tempering their expectations? 

Any litigator should temper expectations before a court. On this issue, which is so central to the well-being of the planet, in which we are all in it together, a court and its judges will surely wish to proceed with real care, in terms of the implications of what they advise. I can’t help thinking that matters of process could come to play a significant role in the outcome of these proceedings. My sense is that—to the extent that litigation can have a significant and dispositive impact on issues related to climate change—the rubber will hit the road in litigation before national courts. A significant role to be played by international courts, in their advisory function, is to offer a framework and outcomes that will allow national courts to give even more meaningful and effective judgments. There is a recent and particularly dismal judgment of the English Court of Appeal, for example (R. (on the application of Friends of the Earth Ltd) v Secretary of State for International Trade/UK Export Finance (UKEF) [2023] EWCA Civ 14), which shows how much remains to be done in helping national judges to take seriously the matter of climate change in terms of existing legal obligations, scientific consensus etc. 

One area where international courts could really make a difference, for example, would be to hone in on the legal consequences of states and other actors failing to take account of the science, which is today rather clear, or failing effectively to assess the impacts of a particular decision or policy on the climate system. To make clear that such failures could have greater consequences—in terms of liability, whether civil or criminal, or state—could be helpful.   

One of the things international courts may be looking at is how can they fulfill their judicial function in interpreting and advising on the law in advisory opinions with the knowledge that they can’t catalyze some breakthrough in legislative efforts, but they can come up with decisions that provide assistance to domestic policy makers or to domestic judges. That interplay between international and national courts is most important, and interesting. 

Do you have any indication of the type of opinions these courts would issue? 

One can hope, but one cannot know what the judges will say. The questions are broad and relatively open-ended in all three cases, and that’s potentially hazardous. In the most recent ICJ advisory opinion, the Chagos opinion, we (7-8 lawyers) spent two years seeking to minimize the wiggle room by narrowing down the questions before the court and putting an emphasis on a finding of fact and drawing the legal consequences that follow. Crafting those questions was done with purpose. In the International Tribunal on the Law of the Sea and the International Court of Justice advisory opinion requests, perhaps the questions really don’t focus as much as they might on questions of fact. Nevertheless, in the written and oral phases participants can hone in on particular issues, and it will be important to try to see if that can be done.  

In my experience, the narrower and more focused the questions, the less wiggle room the court has, and maybe the more likely you might get an answer that is actually useful. The ICJ and ITLOS requests are so broadly drafted! Put yourself in the position of the judges, who will surely be asking themselves: “How do I ensure that I limit my role and activity to a judicial function? It’s my job to interpret and apply the law, to meld issues of fact and law. It is not my function to legislate—although the line between interpretation and application, on the one hand, and legislation, on the other, is not always so easy to define!” 

What happens if the three courts—the ICJ, ITLOS and the Inter American Court of Human Rights—issue conflicting opinions?

It’s a really interesting question. Each court is its own legal order. The Inter American Court of Human Rights has competence to interpret and apply the Inter American Convention on Human Rights. The International Tribunal for the Law of the Sea has authority to interpret and apply the Convention on the Law of Sea. The ICJ is being asked to address a whole raft of international agreements. There are some overlaps—the draft ICJ advisory opinion resolution refers to the Convention on the Law of the Sea and human rights conventions, so the ICJ could in theory adopt an approach that is different from ITLOS, although I think each Court is likely to seek to avoid conflict. I think one of the issues that will be interesting is the sequencing of all of this and who, if you like, gets their neck out there first. There will be some degree of comity between these tribunals. They will want to avoid contradictions. 

What else should people be looking for, or thinking about, as these efforts unfold? 

First I’d say that they should temper expectations about what international courts and tribunals can do in face of legislative inertia. I may be completely wrong on that. For me, the focus of all three initiatives is on process issues. For example, one of the things a court can very usefully do is express an opinion on the science, what is the state of the science, is there a consensus, to the extent there is consensus, what are the legal consequences for a state that fails to have regard to the science in implementing their policy responses? You can imagine that on that issue the courts might want to give answers that are consistent and capable of assisting those to whom their opinions are addressed. 

It is also interesting that the three initiatives seem to be driven by different communities. The Inter American one was brought by the presidents of two different countries, Colombia and Chile, I think. The ITLOS one was brought by a very small group of small island states. The ICJ one was led by another group of small island states, but has obtained very broad support at the UNGA, which is potentially significant in allowing the judges to go further. It’s not apparent that there is much coordination on the three efforts, which could be a good thing, or a bad thing.  

For the United States, these initiatives put the Biden administration in an interesting position because the administration has been strong on climate change. They may have concerns about the legitimacy of the ITLOS exercise and the effectiveness of the ICJ exercise.

There’s one more thing that’s worth saying. Advisory opinions are not legally binding as such on states, but in the case of the ICJ, they do have legal effect on the organizations that ask for them. In the Chagos advisory opinion case, because the request came from the General Assembly, the UN—including the specialized agencies—is in effect bound by the Court’s opinion. So the UN had to accept that Chagos is part of Mauritius and not part of the United Kingdom. That required the UN to change its maps, which it has done. 

Just because these are advisory opinions does not mean they’re unimportant, or can’t have significant practical and real-world consequences, both at the international level and the domestic level. That’s an important point to make. The advisory opinions can be picked up by international organizations, national courts and international courts, they can identify the obligations of states and of other actors, including corporations. That’s where they can have a potentially very significant and useful role.