ClientEarth is an environmental law organization based in the United Kingdom. The McIntosh Foundation awarded ClientEarth its first grant; Winsome McIntosh was the founding board chair. ClientEarth operates all over Europe and China and has a branch in the U.S. registered as ClientEarth US to secure tax benefits to U.S. donors.  Its environmental legal activities are not conducted on behalf of specific human clients, but rather, as the name suggests, with the “earth” as its client.  
ClientEarth was founded in 2007 after founder James Thornton moved to the UK and realized that environmental activism was largely limited to protesting and campaigning and not legal action. Thornton believed that legal action was viewed as risky due to the fact that if the environmentalist plaintiff lost it would be on the hook for the opposing side’s legal costs. He successfully sued the British government and secured a legal cap on legal costs individuals or organizations could be forced to pay if they lost in court. Thornton met with the McIntosh family and they offered to fund his work to establish an environmentalist law firm.  It has since expanded its activities primarily across Europe, but also with work in China and Africa.
ClientEarth operates mainly in Europe and has launched a branch in China. In addition to suing governments and businesses over breaches of EU and domestic environmental law, they also provide draft legislation and commentary to governments. In China the group’s work focusses heavily on advising and training members of the Chinese legal system on environmental public interest law. 
The group provided draft legislation in Germany to phase out the use of coal and sued to stop coal mines from opening.   ClientEarth is also involved in legally challenges concerning environmental issues ranging from logging, fishing regulation, air purity, and chemical manufacturing regulation. 
As the name suggests, ClientEarth considers its client to be the earth itself and as a result does not have human clients when it brings lawsuits. 
In 2022, ClientEarth filed a suit against oil company Shell, alleging that Shell had violated the UK Companies Act by failing to “exercise reasonable care, skill and diligence” regarding a net zero emissions transition.   ClientEarth has been a shareholder in Shell since 2016.
In 2017 ClientEarth reported £11,428,856 ($14.7 million USD as of May 2019) in earnings, of which £2,504,396 ($3.2 million USD) came as donations; £1,092,847 ($1.4 million USD) was from their biodiversity program; £1,092,497 ($1.4 million USD) was from their climate and forests program; and £4,631,087 ($5.98 million USD) was from their strategic litigation program.
Every member of the band Coldplay has financially supported ClientEarth. 
James Thornton is the founding CEO of ClientEarth and has been very involved in legal climate activism. At the beginning of his legal career he worked for the Natural Resources Defense Council.  In 2019 Apolitical named him in the top 100 global influential people in climate policy alongside people like left-wing U.S. Representative Alexandria Ocasio-Cortez (D-NY), billionaire donor and former New York Mayor Michael Bloomberg, and Swedish activist Greta Thurnberg.  In 2018 the book he wrote with his husband, Martin Goodman, titled Climate Earth was awarded the Judge’s Choice award at the Business Book Awards.  He is an ordained Zen Buddhist priest and his Buddhist beliefs are closely tied to the environment. 
In June of 2017, in the wake of the Trump Administration withdrawing from the Paris Climate Agreement, Thornton wrote in the Huffington Post that the Paris Climate Agreement was “the greatest achievement of the 21st century” that “Mr. Trump has now declared himself the enemy of the world’s countries and their peoples” and that “Mr. Trump has self-declared himself the enemy of the world.” He also said that the federal government will stall leaving the agreement until the Trump administration, which he refers to as “an unfortunate blip” will be gone.