This story was updated March 30 with a judge throwing out part of a Trump executive order meant to expand offshore drilling.

The government’s pell-mell race to open up new areas for oil and gas drilling on public lands and waters is running into legal obstacles mounted by conservationists and climate advocates.

Through litigation and procedural maneuvers, opponents of fossil fuel expansion are hoping to overturn key elements of the no-holds-barred oil and gas boom that President Donald Trump and his cabinet have pressed for from the moment they took office.

In the latest case, a federal judge in Alaska sided with environmental groups in a lawsuit over offshore drilling late Friday. The Arctic offshore areas in question—parts of the Outer Continental Shelf in the Beaufort and Chukchi seas—had been protected from fossil fuel drilling by an executive order issued by President Barack Obama. Trump had overturned that order in 2017, and the administration was hurtling toward a lease sale there that it hoped to hold later this year.

The judge determined that Trump didn’t have the authority to revoke Obama’s decisions to withdraw those areas from leasing, or an area of canyons Obama withdrew from leasing in the Atlantic Ocean. That would require action by Congress, the judge wrote.

The previous week, another federal judge ruled that oil leases in Wyoming dating from the Obama years could not be completed without a full-blown environmental impact statement that takes into account the cumulative harms to the climate from emissions of greenhouse gases from the burning of oil.

The judge in the Wyoming case didn’t overturn the leases, which cover more than 300,000 acres of public lands, but the decision did put them on hold for what would probably be a prolonged review under a core statute, the National Environmental Protection Act (NEPA).

“In short, BLM did not adequately quantify the climate change impacts of oil and gas leasing,” U.S. District Judge Rudolph Contreras wrote.

It’s a climate standard that environmentalists have long sought to hold fossil fuel projects to, with only limited success so far. Especially in the fragile Arctic, where the Trump administration has made opening new areas to drilling a priority, they are likely to use the tactic again, along with other objections, in some of the many legal battles to come.

These include:

• Challenging Trump’s executive order reversing Obama’s declaration that had attempted to put offshore waters in the Arctic permanently off limits to drilling—the case the judge ruled on on Friday.
   
• Monitoring the preparation of an environmental impact statement under way for drilling in the Beaufort Sea—which, if it goes ahead, will be challenged in court once it is made final.
   
• Preparing to challenge an imminent new five-year leasing plan for offshore waters nationally.
   
• Challenging drilling in sections of the National Petroleum Reserve-Alaska, a well-established drilling zone, and resisting peremptory changes to its current management plan.
   
• Amassing public comments in opposition to expanded development of the Arctic National Wildlife Refuge (ANWR).

“It took a while to get ramped up,” said Erik Grafe, a lawyer with Earthjustice. “Now it feels like the administration is charging full speed ahead in all areas to try to put its energy and public lands policy into effect.”

Arctic National Wildlife Refuge

The most significant new case that may be challenged under NEPA involves ANWR. Contested for a generation, it includes the 1.6 million-acre coastal plain, a pristine wilderness with vital wildlife habitat and rich reserves of oil. When Republicans pushed through Trump’s tax plan, they authorized leases there.

When the public comment period ended last week for the government’s draft environmental impact statement, more than 1 million comments had been filed in opposition to drilling there.

“At what point are we going to take climate change seriously?” said Adam Kolton, executive director of the Alaska Wilderness League, at a public hearing last June in Washington.

“Climate impacts need to be looked at, and they need to be looked at not just in the context of impacts on wildlife and subsistence and other resources, but how the industry can operate in those conditions. Conditions are changing. Ice road season is changing. There are other serious impacts from that,” he said.

Elizabeth Klein, the deputy director of an environmental and energy center at New York University, said that “the litigation risk is fairly high” once the final impact statement is published.

“What are the cumulative impacts from greenhouse gas emissions? What are the localized impacts? They don’t do a very good job of laying that out, and that’s a problem under NEPA,” she said.

Seismic testing was supposed to begin in the area this winter, but SAExploration, the company behind that plan, has said the testing won’t begin until next winter. The company still needs to attain a permit under the Marine Mammals Protection Act due to potential impacts to a threatened polar bear population in the area, and it has not yet begun that process. That permit will require another public comment period and could also lead to lawsuits.

Offshore Drilling

Just as President Obama was leaving office, he issued an executive order to permanently protect the federal waters of the Chukchi and Beaufort seas from drilling. President Trump tried to overturn that in an executive order of his own a few months later.

Ten conservation groups challenged Trump’s order, and U.S. District Judge Sharon Gleason in Alaska ruled on March 29 that that part of the order was unlawful and invalid.

Gleason noted that the 1953 Outer Continental Shelf Lands Act gave presidents the authority to withdraw areas from leasing, but it did not expressly give them the authority to put previously withdrawn areas back into use. She added that Congress could revoke a withdrawal or change the law to give presidents the right to revoke an earlier president’s withdrawal decision.

The ruling applied to orders Obama issued withdrawing an area of the Atlantic Continental Shelf with 26 canyons considered important for marine life and most of the Outer Contiental Shelf in the Beaufort and Chukchi seas, which the president had noted is an area important to Alaska Natives and marine life.

The Interior Department has been at work on a comprehensive new five-year leasing plan for the offshore waters of the Arctic, as well as the Atlantic and Pacific oceans. The ruling, which the administration is likely to appeal, throws those plans into question now.

[Update: On April 25, Interior Secretary David Bernhardt said in an interview with the Wall Street Journal that the Trump administration would postpone its offshore oil drilling plans indefinitely while the ruling was appealed. ]

Nora Apter, a legislative advocate with NRDC, said before the ruling that the group expected expanded drilling in the Arctic Ocean would be included in the final plan.

The federal government also had been preparing for a Beaufort Sea lease sale that it intended to hold this year. In the wake of Gleason’s ruling, it was unclear whether the Trump administration would continue with the environmental review for that lease sale.

National Petroleum Reserve-Alaska

While a lack of existing infrastructure in the Arctic National Wildlife Refuge and in offshore waters could slow development there, that’s not the case in the National Petroleum Reserve-Alaska.

This area of the Western Arctic has seen decades of development, largely by ConocoPhillips, which has announced some recent, significant discoveries. With a network of existing roads and equipment already nearby, there’s little lag time between the issuing of permits and the beginning of exploratory drilling.

The native village of Nuiqsut, the only community nestled between the National Petroleum Reserve and Prudhoe Bay, recently challenged the federal government for allowing ConocoPhillips to begin exploratory drilling in an area that abuts the community without completing an environmental review.

The company may also find itself with more options available. The Trump administration is in the process of rewriting the integrated activity plan for the area, which dictates which areas of the National Petroleum Reserve-Alaska can be drilled and which areas need to be protected. The current plan was created during the Obama administration and took years to design, according to Klein, who was the Interior Department’s associate deputy secretary while the plan was taking shape.

“The process involved a lot of collaboration with native communities and stakeholders,” said Klein. “Now to upend that process is not cool.”