James Thornton

Professor James Thornton is an environmental lawyer, writer and Zen Buddhist priest. He is founder of ClientEarth, the non-profit environmental law firm with offices in London, Beijing, Brussels, Warsaw, Berlin, Madrid, Los Angeles and Tokyo. 

He is Honorary Professor of Law at the University of Bristol and was Visiting Fellow at Lady Margaret Hall. He taught environmental law at both City University of New York and at New York University School of Law, where he was also editor of the Law Review.

Early career
Before coming to Europe, Thornton worked at Natural Resources Defense Council (NRDC), for whom he set up the citizens' enforcement project focusing on the Clean Water Act, when the Reagan administration dropped its own enforcement. He brought more than eighty cases in the federal courts, won them all, and went on to found the Los Angeles office of the NRDC.

ClientEarth
Thornton founded ClientEarth in 2007. Globally, ClientEarth uses law to work on climate change, nature loss, human health and governance. With a staff over 300, ClientEarth helps write legislation, advises governments, partners with NGOs, and brings litigation, running around 170 cases at any one time.

In early successes, ClientEarth stopped the building of coal plants throughout Europe, enforced clean air laws in more than 20 countries, and increased the capacity of citizen groups to use the law to defend their environmental rights. Uniquely, its teams of lawyers in Europe, Asia and the US use the law of business, finance and property to address climate change and nature loss.

In 2014, China’s Supreme People's Court invited ClientEarth to advise it on the implementation of China’s environmental laws. Since 2015, ClientEarth has trained more than 1,500 of China’s specialist environmental judges and more than 500 prosecutors. The prosecutors report that they have since completed more than 500,000 environmental enforcement proceedings. 

Zen Ordination
Thornton was ordained as a Zen Buddhist priest in the Soto tradition in 2009 in Los Angeles.

Awards
In 2009, New Statesman named Thornton as one of ten people who could change the world. In 2013 The Lawyer identified him as one of the Top 100 lawyers practising in the UK. In 2016, The Financial Times awarded him its Special/Lifetime Achievement Award for innovation in law. He won the Business Green Leader of the Year award three times. In 2025, the Financial Times named him one of the world’s top 20 leaders of global law firms for the last 20 years. 

His book Client Earth (co-authored with Martin Goodman) about setting up a non-profit environmental law firm, won Business Book of the Year and the Santa Monica Library Green Prize.

Thornton is a member of the bars of New York, California, and the Supreme Court of the United States, and a Solicitor of England and Wales. He is a Conservation Fellow of the Zoological Society of London and a fellow of The Ashoka Foundation.