Construction along hundreds of water crossings along Keystone XL pipeline route was thrown into doubt late yesterday, after a U.S. District Court judge in Montana threw out a key permit issued by the U.S. Army Corps of Engineers.

“The ruling comes in response to a lawsuit filed by conservation and landowner groups last year, which challenged the Corps’ failure to adequately analyze the effects of pipelines authorized under Nationwide Permit 12, including Keystone XL, on local waterways, lands, wildlife, and communities,” the U.S. Sierra Club says in a release. The ruling prohibits the Corps “from using this fast-tracked approval process for any pipelines nationwide, including Keystone XL.”

The project could face further legal jeopardy later today, when the court hears a challenge from Indigenous groups and tribes after the Trump administration summarily approved the cross-border segment of the pipeline, where construction began last week. Montana residents are also urging Gov. Steve Bullock to suspend construction during the coronavirus pandemic.

Jared Margolis, senior attorney with the Center for Biological Diversity, called the ruling a “tremendous victory for imperiled wildlife that rely on rivers, streams, and wetlands,” making it clear “that the Trump administration can’t continue to push dirty fossil fuel pipelines while ignoring the devastating impacts they have on the environment.”

The ruling “proves, once again, that we are a nation of laws, no matter how many times powerful forces seek to undermine bedrock American legal protections,” added Glendive, Montana farmer Dena Hoff, a member of the Northern Plains Resource Council. She called for construction to stop during the pandemic, rather than running the risk of “overwhelming our most vulnerable health care systems for a Canadian project that has never proven to be legally viable.”

The Trump administration “has repeatedly violated the law in their relentless pursuit of seeing this dirty tar sands pipeline built,” said Sierra Club Senior Attorney Doug Hayes. “There’s just no getting around the fact that Keystone XL would devastate communities, wildlife, and clean drinking water,” and “should never be built.”

“Farmers and ranchers rely on clean water and land security,” yet TC Energy, the pipeliner formerly known as TransCanada, “continues their efforts to go around the law in order to build their risky pipeline,” said Bold Nebraska founder Jane Kleeb. “Hopefully, this clear directive from the courts will make it clear TransCanada and our own federal government cannot run roughshod over Americans to help out a corporation’s shareholders.”

“Projects like the Keystone XL tar sands pipeline will remain stalled as long as the administration keeps trying to illegally fast-track them,” said Natural Resources Defense Council attorney Cecilia Segal.