Anastasia Kantzelis

Anastasia is an Australian-qualified lawyer specialising in international environmental and natural resources law. Admitted in Victoria and based in London, she works as a public international law consultant and is an Associate Member of Six Pump Court Chambers.

Her work focuses on environmental governance and treaty interpretation. She recently served on the counsel team for a participant in the International Court of Justice advisory proceedings on climate change and, for more than a decade, has advised participants in meetings of climate and other intergovernmental environmental treaty bodies. In 2015 she was a state party delegate to UNFCCC COP21, where the Paris Agreement was negotiated.

She also advises on air quality law and policy—covering regulatory frameworks, comparative approaches, and litigation strategy — and has worked with Stephen Hockman KC and local legal teams on litigation and a major public inquiry. She is an accredited civil and commercial mediator.

Her forthcoming chapter, “The use of jus cogens and erga omnes in international environmental law,” will appear in Christina Voigt (ed.), Environmental Jurisprudence by International Courts: A New Era (Edward Elgar, 2026).