WASHINGTON — A federal judge in Alaska on Wednesday blocked construction permits for an expansive oil drilling project on the state’s North Slope that was designed to produce more than 100,000 barrels of oil a day for the next 30 years.
The multibillion-dollar plan, known as Willow, by the oil giant ConocoPhillips had been approved by the Trump administration and legally backed by the Biden administration. Environmental groups sued, arguing that the federal government had failed to take into account the effects that drilling would have on wildlife and that the burning of the oil would have on global warming.
A federal judge has agreed.
In her opinion, Judge Sharon L. Gleason of the United States District Court for Alaska wrote that when the Trump administration permitted the project, the Interior Department’s Bureau of Land Management’s exclusion of greenhouse gas emissions in its analysis of the environmental effects of the project was “arbitrary and capricious.”
The Willow project has become a political and environmental lightning rod not only for its vast size and its potential ecological damage, but also because the administration of President Biden — which has pledged to pivot the country away from fossil fuels in an ambitious effort to fight climate change — had chosen to legally support it.
In May, the Biden administration drew the wrath of environmental advocates when it filed a brief in the U.S. District Court for Alaska defending the Trump administration’s decision to greenlight the Willow project. The Interior Department said then that the Trump administration’s decision had complied with environmental rules in place at the time.
Environmental groups saw in Wednesday’s decision a vindication of their strong criticism of the Biden administration’s decision not to oppose the drilling plan.
“This is a resounding win for our clients and the climate,” Jeremy Lieb, a lawyer for Earthjustice, which represented multiple plaintiffs in the suit against the Trump administration’s approval of the project, wrote in an email. “The court’s decision vacates the Trump administration’s decision approving the Willow project, and we hope the Biden administration takes this opportunity to reconsider the project in light of its commitment to address the climate emergency.”
A spokeswoman for the Interior Department, Melissa Schwartz, declined to comment on the ruling and a spokesman for the White House did not respond to an emailed request for comment.
A spokesman for ConocoPhillips did not respond to an emailed query about whether the company would appeal the court’s ruling.
Mr. Biden’s decision not to fight the Willow project, despite his pledged commitment to combating climate change, was widely seen as a political effort to win the good will of Lisa Murkowski, the moderate Republican senator seen as a potential ally of the administration in an evenly split Senate.
In recent months, Ms. Murkowski has played a central role in crafting and marshaling Republican support for the sweeping $1 trillion bipartisan infrastructure bill that passed the Senate earlier this month, handing Mr. Biden a major victory in enacting his agenda.
Just before the administration filed its brief to defend the Willow project, Interior Secretary Deb Haaland telephoned Ms. Murkowski to personally let her know of the move.
A spokeswoman for Ms. Murkowski did not respond to an emailed request for comment about the judge’s decision.