For months, protesters from the Standing Rock Sioux and supporters of the tribe have carried on a near-constant demonstration against the Dakota Access pipeline. But in January, President Trump signed an executive action expediting work on the controversial pipeline, and North Dakota’s governor has now ordered the remaining “water protectors” to evacuate their months-long protest site by Wednesday, February 22.

LISTEN: Has Time Run Out at Standing Rock?

Construction on the pipeline was previously halted under President Obama, but construction has now resumed just north of the Standing Rock Sioux reservation. Still, Amy Sisk and Leigh Paterson, who recently produced a documentary called Beyond Standing Rock for Inside Energy, say some questions remain about the legality of Trump’s executive order.

“That’s the big question on everyone’s minds right now,” Sisk says. “And that’s also the heart of the legal challenge that the Standing Rock Sioux Tribe has filed against the pipeline. Their latest legal challenge is asking a federal judge to essentially revoke the pipeline’s permit that was granted under the Trump administration. The reasoning is that the federal government can’t just say it’s going to do one thing and then reverse course without providing some reasonable explanation.”

At the heart of the issue is a part of tribal sovereignty known as “consultation.”

“Consultation basically means that tribes have a seat at the table,” Paterson says. “The federal government has to consult with tribes on certain infrastructure projects. And this consultation process has to happen even if the infrastructure in question doesn’t actually cross the reservation. That’s the case with Dakota Access. The pipeline comes close to the reservation, but doesn’t actually cross through.”

Some Native American activists contend that consultation process never happened — or at the very least, was fundamentally flawed. The Army Corps of Engineers maintains it did reach out to the tribe, and the tribe never responded. Still, Standing Rock Sioux Tribal Chairman Dave Archambault says the larger issue here is not consultation, but consent.

“Archambault told me that ‘this pipeline goes right next to our reservation and we actually want to have a say,’” Sisk says.

The Inside Energy documentary Beyond Standing Rock premieres this week on PBS stations.