The judgment is the latest loss for environmentalists at the conservative Supreme Court, which has recently thrown down measures aimed at protecting wetlands and preventing cross-state air pollution. President Donald Trump has often criticized the government’s environmental assessment process as overly onerous.

The National Environmental Policy Act, signed by President Richard Nixon, is regarded as one of the fundamental pieces of environmental legislation enacted at the start of the modern environmental movement.

Justice Brett Kavanaugh wrote the court’s ruling without any dissent. Ultimately, both liberal and conservative justices agreed with the final verdict.

Kavanaugh ruled that the environmental issues in the case—an 88-mile railway that would transport waxy crude oil from Utah’s Uinta Basin to existing rail networks—were “not close.”

“Courts should afford substantial deference and should not micromanage those agency choices so long as they fall within a broad zone of reasonableness,” Kavanaugh wrote.

“Simply stated, NEPA is a procedural cross-check, not a substantive roadblock,” he later added. “The goal of the law is to inform agency decision-making, not to paralyze it.”

Justice Neil Gorsuch, a conservative, recused himself from the case. He did not explain his decision to withdraw the appeal, but it came after Democrats on Capitol Hill claimed that Denver-based billionaire Philip Anschutz, a major Gorsuch supporter, had a financial stake in the result of the case.

The court’s three liberals, Justices Sonia Sotomayor, Elena Kagan, and Ketanji Brown Jackson, all agreed with the decision but used different rationales. Sotomayor, representing the three, argued that federal agencies should limit their environmental examinations to their respective areas of competence.

The Surface Transportation Board, which handled the evaluation in this instance, is largely concerned with transportation projects, not oil refining.

“Under NEPA, agencies must consider the environmental impacts for which their decisions would be responsible,” Sotomayor wrote. “Here, the board correctly determined it would not be responsible for the consequences of oil production upstream or downstream from the railway because it could not lawfully consider those consequences as part of the approval process.”

The case centered on an 88-mile railway that would transport waxy crude oil from Utah’s Uinta Basin to existing rail networks, making it simpler for the oil and gas sector to transport the commodity to refineries throughout the country.

The Surface Transportation Board performed an environmental evaluation of the railway, as required by law, but environmentalists argued that the review should have been more comprehensive and taken into account the railway’s downstream implications. In other words, they argued that the evaluation should have included the impact of increased crude oil refining.

The Biden administration justified the government agency’s less thorough review. In that regard, the Biden and Trump administrations were similar.

During his first administration, Trump criticized NEPA-mandated environmental assessments as time-consuming and inefficient.

“These endless delays waste money, keep projects from breaking ground, and deny jobs to our nation’s incredible workers. From day one, my administration has made fixing this regulatory nightmare a top priority,” Trump said at the White House in 2020.

Last year, Congress passed revisions to the statute that, in many situations, limit the evaluations to 150 pages instead of enabling the studies to be thousands of pages long.

During the discussions, advocates of the train project said that it is difficult for an agency to analyze all of the downstream consequences in a 150-page paper.

Eagle County, Colorado, and other environmental groups sued over the review, claiming that a more restricted investigation of potential environmental problems would have national implications.

“This case is bigger than the Uinta Basin railway,” Sam Sankar, vice president of programs for Earthjustice, which is representing some of the plaintiffs, told CNN in December. “The fossil fuel industry and its allies are making radical arguments that would blind the public to the obvious health consequences of government decisions. The court should stick with settled law instead. If it doesn’t, communities will pay the price.”