Foley Hoag LLP assisted the Republic of Sierra Leone and the Republic of Mozambique in successfully obtaining from the International Tribunal for the Law of the Sea an advisory opinion on the legal obligations of States concerning climate change under the UN Convention on the Law of the Sea.

In the unanimous opinion delivered on May 21, 2024, the Hamburg-based Tribunal, which was created by the Convention, determined that States are obligated to take all necessary measures to prevent, reduce, and control marine pollution from anthropogenic greenhouse gas emissions. This requires States to adopt and enforce national laws to implement, based on the best available science, the temperature goal set out in the Paris Agreement on climate change of limiting the global temperature increase to 1.5 degrees Celsius above pre-industrial levels. Recognizing that not all States are similarly situated, the Tribunal affirmed that implementation of this obligation may vary according to States’ capabilities and available resources.

The Tribunal determined as well that States are under the specific obligation to protect and preserve the marine environment from climate change impacts and ocean acidification.  Where the marine environment has been degraded, States may be required to restore marine habitats and ecosystems.
  
Christina Hioureas, Foley Hoag partner and Global Co-Chair of its International Litigation and Arbitration Department, argued on behalf of Sierra Leone. She said that the Tribunal’s opinion “unambiguously confirms the obligations that international law imposes on States to take effective action to regulate anthropogenic greenhouse gas emissions, obligations that give States the corresponding right to take such measures.”

Partner Andrew Loewenstein, who argued for Mozambique, said the opinion is a “landmark in the history of international environmental law that provides critical benchmarks for holding States accountable for taking the measures necessary to protect not just highly vulnerable States like Sierra Leone and Mozambique, which have contributed the least to climate change, but marine ecosystems around the world and the people who depend upon them.”

The Foley Hoag team was composed of Christina Hioureas, Andrew Loewenstein, Diem Huong Ho, Juan Pablo Hugues, Peter Tzeng, Ivana Mariles Toledo and Lucia Rueda, with assistance from Alexander Small and Katie Weiner.
 
Foley Hoag’s co-counsel was Professor Phoebe Okowa, member of the UN International Law Commission (Kenya); Professor Charles Jalloh, member of the UN International law Commission (Sierra Leone); and then Professor Dire Taldi, former member of the UN International Law Commission (South Africa), supported by the Open Society Justice Initiative and scientists from the Union of Concerned Scientists, Sean O’reilly, Barrister Plowman Chambers, Hong Kong, and Olivia Flash, research assistant.