While policymakers continue to dither in the face of an escalating climate crisis, the courts have increasingly emerged as unlikely champions of environmental accountability. Where legislative inertia reigns, legal action—often led by youth and vulnerable communities—has become a powerful lever to confront ecological harm and force state obligations into sharper relief.

The year 2025 is proving particularly consequential for climate litigants. In early July, the Inter-American Court of Human Rights (IACtHR), at the request of Chile and Colombia, issued an advisory opinion that reshapes the legal landscape of climate responsibility. The Court offered expansive guidance on state obligations—not only in upholding substantive rights threatened by the climate emergency, but also in protecting procedural rights and safeguarding vulnerable populations, including children, environmental defenders, women, and Indigenous communities.

The opinion doesn’t merely ask states to refrain from harm. It mandates action. States, the Court insists, are required to exercise “reinforced due diligence” to address foreseeable climate-related damage. It recognizes the right to a safe climate as a fundamental human right and elevates the prohibition against irreversible environmental harm to the status of jus cogens—non-derogable norms on par with the prohibitions against slavery, torture, and genocide.

Striking a novel and distinctly Latin American chord, the Court also declared that Nature itself—and its constituent elements—should be recognized as legal subjects. In doing so, it aligned itself with a growing jurisprudential current known as “ecological constitutionalism,” a doctrine gaining traction in the Global South that extends rights not just to people but to the planet.

Just weeks later, on July 23, the International Court of Justice (ICJ) issued its own landmark advisory opinion, one that promises to reverberate far beyond The Hague. For fossil fuel-dependent states and industries, the Court’s message was stark: the era of unaccountable emissions is nearing its legal end.

The origins of this opinion are as compelling as its conclusions. It began in 2019 with a bold initiative by Pacific Island students at the University of the South Pacific, backed by the government of Vanuatu. Their question was simple but seismic: could the production and consumption of fossil fuels constitute an internationally wrongful act?

The ICJ’s answer: yes.

Unanimously, the Court ruled that states producing and consuming fossil fuels in ways that exacerbate climate change may indeed be committing internationally wrongful acts. The ruling also addressed the profound consequences of climate inaction, echoing Vanuatu’s submission that highlighted the cultural and territorial losses caused by forced displacement due to climate shocks. “The forced displacement from ancestral lands and ecosystems leads to grave cultural losses,” the submission warned. “It impairs territorial sovereignty and inhibits the affected peoples from making a free choice about their futures.”

The Court went further, stating unequivocally that countries have a legal obligation to limit global temperature rise to 1.5°C above pre-industrial levels, as established in the Paris Agreement. It emphasized that national climate action plans—so-called “nationally determined contributions”—must reflect each country’s “highest possible ambition” and be subject to international standards of due diligence. No longer could nations cloak insufficient climate policies in the language of sovereign discretion.

The opinion also took aim at the long-standing impasse over climate reparations. Historically, climate negotiations have allowed wealthy nations to make voluntary contributions to “loss and damage” funds, avoiding direct accountability. The ICJ dismantled that firewall. Reparations, it declared, are not optional. They are a legal obligation under customary international law. Both nations and injured individuals have the right to seek compensation from historically high-emitting states—a major departure from past climate diplomacy.

This shift is crucial for climate-vulnerable economies dependent on agriculture, fishing, and tourism, which now face mounting environmental disasters with diminishing resources. It is also a direct challenge to states that have argued that the diffuse and cumulative nature of greenhouse gas emissions makes legal responsibility impossible to assign.

The ICJ disagreed. Emissions may be cumulative, it noted, but science allows for the calculation of each state’s contribution—historical and current—to global warming. Accountability, in other words, is not a matter of ideology, but of math.

The consequences of this decision are already being felt. Vanuatu’s climate minister, Ralph Regenvanu, has publicly called out Australia, a major fossil fuel exporter and regional neighbor. “Australia,” he stated bluntly on national radio, “is committing internationally wrongful acts as it is sponsoring and subsidising fossil fuel production and excessive emissions.” He called on Canberra to cease such conduct and begin making reparations.

Litigation, once a distant and uncertain frontier for climate activism, has become a potent tool in international law. And this legal revolution is not limited to Latin America or the Pacific. A recent petition to the African Court on Human and Peoples’ Rights seeks to replicate the momentum of the ICJ and IACtHR rulings, this time with a focus on African states.

For fossil fuel lobbies and the politicians they bankroll, these developments are deeply unwelcome. The days when governments could hide behind vague promises and voluntary schemes are drawing to a close. Courts are beginning to translate the moral urgency of the climate crisis into binding legal obligations. And in doing so, they are reshaping the future of environmental governance—one ruling at a time.