Among like-minded advocacy groups, the Center for Biological Diversity has consistently filed the most environmental lawsuits against the federal government over the past decade. The first year of President Donald Trump’s second term still broke records.
The organization has filed 83 such lawsuits since Trump retook office last year, exceeding the pace it set during Trump’s first term, when it sued the government 266 times.
A NOTUS analysis of environmental litigation data collected by Columbia Law School’s Sabin Center for Climate Change Law shows that the nonprofit is just one of a host of environmental groups that are responding to the Trump administration’s deregulatory agenda and funding cuts with full force in the courts.
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But as these groups have widened the scope and pace of their litigation, it’s opened them up to new vulnerabilities.
“It has made our litigation more difficult and our federal court litigation more challenging,” Joanne Spalding, the legal director at the Sierra Club, told NOTUS. “It certainly changes the way we frame the arguments.”
The Sierra Club filed or intervened in more than 100 lawsuits in 2025. The organization has also intervened in multiple lawsuits this year, including the first major piece of litigation against the federal government for its rollback of the 2009 finding that greenhouse gas emissions are a danger to public health, which has underpinned climate action.
Plaintiffs suing over everything from the end of climate justice funds to the rollback of electric vehicle programs have seen relative success in district courts. But an influx of Trump-appointed judges in appeals courts means that advocacy organizations could face an uphill battle in maintaining that success. As does the federal government’s decision to roll back guidance for federal judges on environmental issues. The courts have ruled in favor of the administration in more than half the cases since Trump took office, according to an analysis by The New York Times.
The administration has appealed multiple losses already, and members of Trump’s team have suggested they’ll file more appeals soon.
For some groups, litigating in the Trump era has meant taking on a broader variety of legal arguments than ever before. The Sierra Club has filed cases about public records requests, emergency power orders that keep aging coal plants open and other issues that didn’t come up during previous administrations, Spalding said.
Earthjustice — a national group that does not file its own litigation but represents other groups in court — has gotten involved in cases about immigration detention facilities and federal funding in a departure from its usual slate of topic areas, Sam Sankar, the senior vice president of programs for the organization, told NOTUS.
Jason Rylander, the legal director of the Center for Biological Diversity’s Climate Law Institute, called it “reacting defensively to all the various ways that this administration is undermining the law.”
This broadened legal strategy could backfire on these groups. Appeals courts and the Supreme Court have thrown out multiple environmental cases in recent years over findings that advocacy groups don’t have the proper standing, or qualifications, to sue over some issues.
The uptick in lawsuits has also complicated an already tenuous public perception of environmental groups, some of which are on shaky ground because of internal dysfunction and a drop in support. The litigation ramp-up has prompted attacks from Trump himself, who has called environmental litigation “frivolous,” and from critics who say environmental lawsuits are costly for taxpayers, disrupt manufacturing and jobs and give the courts too much power around environmental decision-making.
Criticism of the groups’ legal approach overlooks that the “progressive NGO legal community is far, far smaller than Trump’s propaganda or industry propaganda would allow you to suggest,” Sankar at Earthjustice told NOTUS.
And not all environmental groups are flooding the courts with lawsuits.
“In the first administration, I think we wanted to challenge every rollback that came down, and we’re being more focused this time and looking at where we can have the greatest impact,” said Michael Wall, the chief litigation officer at the Natural Resources Defense Council.
The group filed 163 lawsuits against the first Trump administration, according to its own tracker, and has reported filing or intervening in more than 30 cases in Trump’s second term.
“We’ve sued, I think, every administration for the last 50 years in one way or another,” Wall said. “This administration, in some ways, has made our jobs both more challenging and easier, because it doesn’t seem to be particularly concerned about compliance with the law. It seems to have a kind of move fast and break things approach to environmental protection.”
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