Earthjustice (originally Sierra Club Legal Defense Fund) is a nonprofit public interest organization based in the United States dedicated to litigating environmental issues.

The case ultimately forced the Walt Disney Company to drop its plans to develop an enormous ski resort in the Mineral King valley in California's Sierra Nevada Range.

[16] In 1993, the organization (still then known as the Sierra Club Legal Defense Fund) filed a lawsuit to block the development of the New World gold-silver-copper mine that was planned to be sited about four miles from the northeast entrance to Yellowstone National Park.

[18] In the 2006 Supreme Court case Massachusetts v. Environmental Protection Agency, Earthjustice attorneys helped a coalition of state governments and conservation groups force the U.S. Environmental Protection Agency (EPA) to fight global warming by limiting greenhouse gas emissions.

[21][22] However, on August 9, 2018, the court ruled that chlorpyrifos must be banned within 60 days from that date[23] In 2010, Earthjustice launched a fundraising campaign using the location-based social networking app Foursquare.

The ad campaign, which ran in billboards in San Francisco's BART system, gained national recognition as one of the first successful nonprofit uses of Foursquare.

This success was featured in media outlets such as The New York Times, Mashable, and MacLife magazine, as well as books such as Carmine Gallo's The Power of Foursquare.