The case is captioned Committee on the Judiciary, United States House of Representatives v. Donald F. McGahn II, but it might as well be called Rule of Law v. Donald J. Trump. On Monday, rule of law won.

U.S. District Judge Ketanji Brown Jackson ruled that former White House counsel Donald McGahn had to comply with a House subpoena for his testimony. But the import of her decision goes beyond the immediate question of whether McGahn will testify. He had already provided evidence of President Trump’s obstructive behavior in the inquiry by former special counsel Robert S. Mueller III, and he was gone from the White House long before the Ukraine episode.

As a result, in many ways the specifics of McGahn’s testimony are less critical than the principle that the House is entitled to obtain it. At stake is whether the administration’s bloated view of presidential power will triumph over years of precedent and constitutional design, diminishing the authority of the judiciary and Congress.

In seeking to block McGahn and other senior White House officials from testifying, the administration made two remarkably sweeping claims, both of which would swell presidential authority to dangerous proportions.

The first is that Congress has no right, period, to summon senior-level presidential aides to testify. Note, the argument is not that certain confidential communications between aides and the president should remain protected by executive privilege; questions about the scope of that privilege would remain for another day. Rather, the administration contends that, if the president decrees his aides should not appear, they enjoy “absolute” immunity from having to turn up, subpoena be damned.

The second, even more alarming, is that federal judges have no right to referee these disputes between the legislative and executive branches. In this conception, the separation of powers inevitably becomes the primacy of the presidency. Checks and balances yield to presidential whim, as Congress is powerless to compel testimony and the courts must stand aside.

If all this sounds familiar, that is because this approach reflects the expansive version of executive authority outlined by Attorney General William P. Barr in his speech this month to the Federalist Society. Jackson made no mention of Barr’s speech, but her 118-page ruling stands as a rebuke to his vision.

The administration’s “contentions about the relative power of the federal courts, congressional committees, and the President distort established separation-of-powers principles beyond all recognition," she warned.

In the constitutional scheme of checks and balances, Jackson noted, “the Judiciary’s constitutional check is the power to tell the other branches what the law is.” The Justice Department’s “odd idea that federal courts’ indisputable power to adjudicate questions of law evaporates if the requested pronouncement of law happens to occur in the context of a dispute between branches appears nowhere in the annals of established constitutional law.”

As to Congress’s authority to summon White House aides to testify, Jackson said the administration’s assertion of “absolute testimonial immunity” has “no foundation in law” and “conflicts with key tenets of our constitutional order.”

This is far from the first tussle between Congress and a president over obtaining testimony from a top aide; administrations of both parties have been prickly about letting the president’s closest advisers be hauled before Congress.

Still, there are scant court rulings on the issues, as Jackson noted, not because courts have no business in the matter, but because the other two branches, with other weapons at their disposal (Congress has the power of the purse, for example) usually manage to work out these disputes on their own.

An uncanny parallel to the McGahn litigation arose a dozen years ago, during the George W. Bush administration, when the House Judiciary Committee subpoenaed former White House counsel Harriet Miers to testify in an investigation into the firing of U.S. attorneys.

Then, U.S. District Judge John D. Bates ruled against the president who appointed him, rejecting the Bush administration’s claims that its senior aides had absolute immunity from testifying and that the courts had no role to play in the stand-off. As the matter was ultimately resolved (Miers testified, after a new president was elected), the parties dropped their appeals — and the Bates opinion was left in place. “The more things change, the more they stay the same,” Jackson observed about the parallels between the two cases.

Things have stayed the same, but they have also changed, in significant and ominous ways. This administration has far outdone its predecessors in thumbing its nose at oversight — not only resisting the McGahn testimony but also challenging the authority of congressional committees and prosecutors in other cases now edging their way to the Supreme Court: the request by the House for access to Trump’s tax returns; a grand jury subpoena to Trump’s accountants for his financial records. The administration has announced it will appeal the McGahn ruling, as well.

“Stated simply, the primary takeaway from the past 250 years of recorded American history is that Presidents are not kings,” Jackson observed toward the close of Monday’s ruling. The coming months will test the courts and help illuminate how true that seemingly obvious maxim remains.

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