The Legal Foundations for Fossil Fuel Phaseout: An Open Letter to the Co-Hosts and Participants of the First Conference on Transitioning Away from Fossil Fuels

An open letter from 252 legal experts to the participants of the First Conference on Transitioning Away from Fossil Fuels, asserting that states have binding international legal obligations to phase out fossil fuels to prevent significant climate harm.

• Legal scholars and practitioners argue that states have binding obligations under multiple sources of international law to phase out fossil fuels, citing the International Court of Justice (ICJ) confirmation that states must use all available means to prevent significant harm to the climate system by avoiding fossil fuel production and use.
• The duty to phase out fossil fuels is derived from several legal frameworks: customary international law (the duty to prevent transboundary harm), human rights law (the right to a healthy environment), the law of the sea (UNCLOS obligations to control marine pollution), and climate treaties such as the UNFCCC and the Paris Agreement.
• The authors contend that the Paris Agreement's goal of limiting temperature rise to 1.5c is impossible without rapidly reducing oil, gas, and coal, and that continuing fossil fuel subsidies contradicts the agreement's aim of aligning financial flows with low-GHG pathways.
• States are required to exercise due diligence in their climate actions, which means measures must be informed by science, effectively enforced, and progressively more demanding. Proven emission-reduction methods at the source must take precedence over speculative technological interventions.
• The letter asserts that fossil fuel expansion is 'presumptively contrary to legal duty' and that states face legal consequences, including duties of cessation and reparation, for failing to regulate fossil fuel companies or for financing GHG-emitting activities.
• The level of obligation varies by state capability under the principle of common but differentiated responsibilities and respective capabilities (CBDR-RC). Developed states must take more demanding measures and provide finance, technology, and capacity-building to developing countries, particularly least developed countries (LDCs) and small island developing States (SIDS).
• The authors argue that Investor-State Dispute Settlement (ISDS) mechanisms should not be allowed to impede a state's compliance with climate obligations or make the phaseout of fossil fuels prohibitively expensive.

APA

Center for International Environmental Law (n.d.). The Legal Foundations for Fossil Fuel Phaseout: An Open Letter to the Co-Hosts and Participants of the First Conference on Transitioning Away from Fossil Fuels. https://www.ciel.org/wp-content/uploads/2026/04/fossil_fuel_phaseout_legal_letter_santa_marta.pdf.pdf

Chicago

Center for International Environmental Law. The Legal Foundations for Fossil Fuel Phaseout: An Open Letter to the Co-Hosts and Participants of the First Conference on Transitioning Away from Fossil Fuels. n.d. https://www.ciel.org/wp-content/uploads/2026/04/fossil_fuel_phaseout_legal_letter_santa_marta.pdf.pdf.

Wikipedia

{{cite press release |author=Center for International Environmental Law |title=The Legal Foundations for Fossil Fuel Phaseout: An Open Letter to the Co-Hosts and Participants of the First Conference on Transitioning Away from Fossil Fuels |url=https://www.ciel.org/wp-content/uploads/2026/04/fossil_fuel_phaseout_legal_letter_santa_marta.pdf.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@misc{centerforinternationalenvironmentallawndlegal, author = {{Center for International Environmental Law}}, title = {{The Legal Foundations for Fossil Fuel Phaseout: An Open Letter to the Co-Hosts and Participants of the First Conference on Transitioning Away from Fossil Fuels}}, publisher = {Center for International Environmental Law}, url = {https://www.ciel.org/wp-content/uploads/2026/04/fossil_fuel_phaseout_legal_letter_santa_marta.pdf.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }