McFadden also wrote, quoting from another Supreme Court case, “Intervening in a contest between the House and President over the border wall would entangle the Court ‘in a power contest nearly at the height of its political tension’ and would ‘risk damaging the public confidence that is vital to the functioning of the Judicial Branch.'”

Lawmakers expressly approved only $1.375 billion in the weeks after the shutdown, to go toward funding to 55 miles of wall along the southern border. But, Trump said that was inadequate, and he pushed ahead by moving funds from other Homeland Security projects previously approved by legislators. In his budget request earlier this year, Trump formally requested another $8.6 billion from Congress, saying that would be sufficient to build more than 700 miles of wall.

The emergency-appropriated funding alone could be used to build more than 230 miles of barriers.

At a hearing in May, McFadden hinted that courts should stay out of the matter — and suggested an appeal was imminent regardless.

“I’m not sure how much necessarily our views will carry the day for the courts above us,” McFadden said at the hearing.

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Disagreement already has been brewing in the lower courts, setting the stage for appellate panels to step in. Gillam, the Northern District of California judge who ruled last month that Trump was likely breaking the law by reallocating the wall funds, blocked some projects slated for immediate construction in Yuma and El Paso.

“In short, the position that when Congress declines the Executive’s request to appropriate funds, the Executive nonetheless may simply find a way to spend those funds without Congress does not square with fundamental separation of powers principles dating back to the earliest days of our Republic,” Gilliam wrote.