As planned, the Dakota Access pipeline would run 1,100 miles from oil fields in northwest North Dakota to a refinery and port in Illinois. Hundreds of people, many of them from Native communities or nations, have gathered on tribal land near the Missouri River since April to protest the pipeline’s construction. The camps are one of the largest Native protests in decades.

In July, the Standing Rock Tribe sued the Army Corps of Engineers, the federal agency which approved the pipeline. The tribe claimed that the pipeline’s construction would destroy nearby sacred and burial sites, and that, if the pipeline ever leaked or failed, it would pollute the tribe’s drinking water. It sought a temporary injunction to halt its construction. I wrote about the tribe’s case this week.

On Friday, the court declined that injunction request with a 58-page ruling. (The Department of Justice, apparently waiting for the decision, issued its own statement blocking the pipeline minutes later.)

The judge, James Boasberg of the D.C. district court, said that the Army Corps had sufficiently followed federal law in approving the pipeline. The tribe’s claims that the pipeline crossed archeological sites were moot, since most of those sites were on private property, he said. And he seemed to lament that the injunction was sought under the National Historic Preservation Act and not the Clean Water Act, where he hinted that the tribe would have had sturdier standing.

“This Court does not lightly countenance any depredation of lands that hold significance to the Standing Rock Sioux,” wrote Boasberg. “Aware of the indignities visited upon the Tribe over the last centuries, the Court scrutinizes the permitting process here with particular care. Having done so, the Court must nonetheless conclude that the Tribe has not demonstrated that an injunction is warranted here.”

Of course, all this will change now that the executive has stepped in. “This federal statement is a game changer for the Tribe and we are acting immediately on our legal options, including filing an appeal and a temporary injunction to force DAPL to stop construction,” said a statement from the Standing Rock Sioux on Facebook.

While the government’s block is temporary, the pipeline’s future now looks much more uncertain than it did hours ago. Most of the pipeline will be built on private land owned by Energy Transfer Partners, but it still needs Army Corps approval to cross federal waterways. Given the outcry from climate activists, the Obama administration may be more willing to cancel the pipeline’s federal permits, as it did with the Keystone XL pipeline last year.

I found it particularly interesting that the administration’s statement called out the National Environmental Policy Act (NEPA). That law requires federal agencies to account for environmental risks and hazards when they approve a project. Earlier this year, President Obama decreed that the NEPA process should account for the costs of greenhouse gas emissions—a potential opening for federal agencies to obstruct a huge fossil-fuel infrastructure project like Dakota Access.