Here.

“It’s the flip-side of the question everyone was asking last year, ‘Why doesn’t Obama just put the kibosh on Dakota Access?’” said Sarah Krakoff, a professor of tribal and resources law at the University of Colorado Boulder. “Well, it’s not really his role. It’s the Army Corps’s role, and that’s still true today.”

“Trump can’t, with the stroke of a pen, just make the Dakota Access pipeline happen. He just can’t. He doesn’t have that authority. It’s his agency’s authority, and he can’t revoke the laws that the agency just found that it has to comply with,” she added.

She added too that the executive orders seemed to be written in a typical way. Instead of commanding agencies to ignore congressionally passed law, the orders request that they expedite or reconsider previous judgments. “Executive orders are legal orders—they’re law—but they can’t contravene legislative enactments. So an executive order can’t say, ‘Ignore the [National Environmental Policy Act] and give me a pipeline,’” she told me.

“If the federal law gives decision-making authority to a particular official, that official has to make the decision,” said John Leshy, a professor of real property law and a former general counsel to the U.S. Department of the Interior. “But there’s some murkiness about what the president can do. The decision maker can say no, and then the president can fire them and replace them with someone who would. But that takes time.”

Krakoff added that it would attract judicial suspicion if the Army Corps of Engineers suddenly decided that it didn’t have to make an environmental-impact statement for the Dakota Access pipeline after saying that it did just weeks ago.

“It would be hard for them to turn around on a dime and say, ‘We got this piece of paper from the president and now we don’t think that’s necessary,’” she said. “If the agency were to take a different route, legally, now, I would strongly suspect that that would be subject to litigation.”