From 24 to 29 April, the first international conference on transitioning away from fossil fuels (TAFF)—co-hosted by the Colombian and Dutch governments—will take place in Santa Marta, Colombia. This event reflects a growing global consensus: phasing out fossil fuels is indispensable to meaningful climate action. Yet, despite this political momentum, significant legal barriers persist. Among the most formidable is the system of international investment law, particularly the mechanism of investor–state dispute settlement (ISDS), as also recognized in one of the pillars of the Santa Marta TAFF Conference. One way to counter this type of legally entrenched climate obstruction is for States to clarify that their right to climate action is a new peremptory norm of international law, as per Article 64 of the Vienna Convention on the Law of Treaties (VCLT). As we discuss below (and here), recognizing the jus cogens status of this right would likely limit fossil fuel investors’ ability to strategically deploy ISDS mechanisms.

ISDS as a Structural Constraint on Climate Policy

It is increasingly acknowledged that international investment agreements (IIAs) can obstruct the energy transition. Treaties such as the Energy Charter Treaty (ECT), as interpreted by arbitral tribunals, grant extensive protections to investors, including those in the fossil fuel sector. These protections often translate into substantial financial risks for States implementing climate policies. While the Paris Agreement has solidified international commitment to reducing greenhouse gas emissions, empirical research suggests that mitigation measures affecting upstream oil and gas projects could expose States to ISDS claims amounting to as much as USD 360 billion globally. To date, nearly USD 83 billion has already been awarded to fossil fuel investors through arbitral decisions and settlements.

One commonly proposed solution is the termination of investment treaties. Ahead of Santa Marta, Gustavo Petro, the President of Colombia has already announced that Colombia will withdraw from the investor-State dispute settlement system. Yet, terminating treaties faces practical and legal obstacles. Many treaties contain “sunset clauses,” which extend investor protections for up to 20 years after termination. Additionally, with over 3,000 bilateral investment treaties (BITs) currently in force, withdrawal is both time-consuming and politically challenging, albeit a coordinated withdrawal could reduce several obstacles (as illustrated by the EU coordinated withdrawal from the ECT).

Climate Action as Jus Cogens

Against this backdrop, we propose that the recognition of States’ “right to climate action” as a jus cogens norm of international law could be considered a complementary strategy to limit ISDS-driven climate obstruction. If such a right is considered peremptory, investment agreements are either to be interpreted in radically new ways, so as to exclude fossil fuel investors from protection, or be declared (partially) null and void in accordance with Article 64 of the Vienna Convention on the Law of Treaties (VCLT). The jus cogens nature of climate action should categorically be understood as entailing no payment to fossil fuels investors for measures limiting fossil extractivism, such as carbon taxes or fossil fuels phase outs. This is because the very costs of these disputes are the main barrier to climate action. In other words, through the superior hierarchical normativity of the right to climate action, States should be able to break free from fossil investors feigned victimization and their threats to climate policy.

This jus cogens right to climate can be understood as the counterpart to an emerging obligation to act on climate change. Notably, the Inter-American Court of Human Rights, in its 2025 Advisory Opinion on the Climate Emergency (AO-32/25), recognized an obligation to protect the climate as having jus cogens character. While this development is significant and has been considered plausible by authoritative legal scholars, it has not been without criticism. Scholars have pointed out that jus cogens norms are often disregarded in practice, particularly where political incentives for enforcement are weak. Moreover, States may resist the recognition of environmental peremptory norms due to concerns about sovereignty.

The introduction of a right to climate action addresses some of these concerns. Unlike obligations, which are typically invoked against States in judicial or quasi-judicial forums, rights can be mobilized by States themselves. In the context of ISDS, this distinction is crucial. A jus cogens right to climate action could serve as a legal defense, enabling States to justify regulatory measures that would otherwise trigger liability under investment treaties.

Doctrinally, this right can be grounded in the principle of self-determination, which has a widely accepted jus cogens status (and is included in the non-exhaustive list of jus cogens norms by the International Law Commission). In light of the overwhelming scientific consensus on anthropogenic climate change and its existential implications, the ability of States to safeguard a habitable environment becomes intrinsic to their capacity for self-determination. Climate change-caused emergencies such as sea-level rise, heavy rains, desertification, or droughts are already causing food insecurity, forced displacement, and a fundamental alteration to the environmental conditions that are necessary preconditions to pursue choices about economic, social, or cultural development.

Climate mitigation policies—such as phasing out fossil fuels, imposing carbon taxes, or revoking extraction permits—are thus not merely regulatory choices but expressions of a fundamental legal entitlement.

State practice and opinio juris further support this development. Increasingly, investment treaties include provisions affirming the State’s “right to regulate,” often explicitly referencing environmental protection and climate action. Additionally, submissions to the International Court of Justice in the proceedings to its Advisory Opinion on climate obligations reveal broad recognition of the normative importance of climate protection.

Restoring Regulatory Space

Importantly, understanding climate action as a jus cogens right may enhance both sovereignty and enforceability. States facing arbitration lodged by fossil fuels investors would have a tangible incentive to invoke this right, as it could shield them from substantial financial liability. In an era marked by renewed emphasis on sovereignty and the strategic use of ISDS by fossil fuel interests, such a doctrinal tool could rebalance the relationship between investment protection and public policy. Crucially, the right to climate action empowers States to pursue essential climate policies, bolstering sovereignty and the right to self-determination. Rather than exposing the fragility of international law, it provides a pragmatic mechanism for aligning legal frameworks with urgent global priorities.

The jus cogens right to climate action is not a panacea. It will not eliminate all tensions between contemporary economic policies and climate governance. Yet, it represents a meaningful step toward an international legal order in which the pursuit of collective survival—preserving life on Earth—is not hindered by prohibitive legal and financial constraints.