The movement to make polluters pay recently scored its biggest win yet.

In a groundbreaking, 500-page advisory opinion, the International Court of Justice formally determined that countries are obligated to act on climate change, and those that fail to do so should be held accountable.

According to the court’s opinion, everything from introducing fossil fuel-friendly policy to licensing new oil and gas projects—even failing to regulate companies within your country’s borders—can be considered a breach of international agreement.

Of course, this massive victory didn’t happen overnight—it’s been years in the making.

It all started back in 2019, when a group of law students from the Pacific Islands set out to answer a big question: if the Paris Agreement and other global treaties aren’t enough to hold the world’s biggest polluters accountable, what can be done?

Their idea of bringing this unique case to the ICJ was picked up by Vanuatu, and in 2021, the island nation called on the World Court to issue an opinion on countries’ legal climate obligations. Three years later, the ICJ heard arguments from more than 100 nation-states and global organizations—and now, they’ve finally shared their advisory opinion with the world.

This is a big deal.

While not legally binding, any opinion from the World Court carries real weight and authority—which means the world of climate litigation just gained an incredibly powerful asset. Experts expect to see the opinion used in the nearly 3,000 climate cases in progress around the world. Small nations are already exploring how they can use this ruling to seek reparations from the world’s biggest polluters. Looking ahead, national governments are counting on the ruling to set the stage for negotiations at COP30 this year.

For the first time in history, holding wealthy nations accountable for their historic emissions and climate damages isn’t just a hypothetical, but a distinct possibility. And the countries that have suffered the most from the climate crisis, despite contributing the least, can now take action.

This landmark ruling is a heartening reminder that progress is still happening. And no matter how hard the Trump administration tries, they can’t stop the rest of the world from recognizing the reality of the climate crisis and choosing to act.

Let’s celebrate this win in the best way we can: by continuing our efforts to make polluters pay!