Washington (CNN) The judicial branch just delivered a sharp jab to the chin of President Donald Trump , in a foreboding omen for his strategy for thwarting investigations that threaten his presidency.

When a federal judge ruled Monday that the President's longtime accounting firm Mazars must hand over his financial records, he did not just deliver a win to stonewalled Democrats.

He made a sweeping point about Congress' power to hold a President to account -- in an argument that will reverberate throughout Trump's attempt to fend off an oversight offensive.

Trump is appealing the decision, and long court battles loom -- so Monday's ruling was a setback in a much longer war, a factor that offers Trump a significant political advantage.

And typically, his response signaled that he has no intention of backing down and will take each bout in his battle against Congress as far as he can, potentially to the Supreme Court

But Monday put down an early marker in the separation-of-powers feud between Congress and the White House and may hint at how other court battles between Democrats and Trump may pan out.

"It is a good opinion. It sets a very good bedrock framework for how all of these skirmishes between House committees and the White House are going to go," Preet Bharara, former US attorney for the Southern District of New York, said on CNN's "Anderson Cooper 360."

Depending on how the White House reacts to any eventual court orders that contravene the President's wishes, Monday's drama may also have brought a constitutional crisis one step closer.

Former FBI general counsel James Baker told CNN's Wolf Blitzer on Monday that Congress had not always exercised powers inherent in the Mazars case, and had over the years ceded power to the presidency.

"I think it is a recognition that Congress has a lot of power under the Constitution -- that is just the case," Baker said on "The Situation Room." "This is them taking some of this back by trying to enforce this subpoena, so the ruling from the court doesn't surprise me."

Trump's legal team had argued that Congress is on a crusade to overturn material that the Democrats could use to embarrass him now and in the 2020 presidential election.

But House Oversight Chairman Elijah Cummings, a Maryland Democrat, called the ruling a "resounding victory for the rule of law and our constitutional system of checks and balances."

Empty chair

Democrats did not have it all their way Monday.

And McGahn confirmed that he would not show up for a hearing Tuesday of the House Judiciary Committee -- which is now certain to turn into a theatrical venting before an empty witness chair.

His lawyer, William A. Burck, argued that since McGahn was facing contradictory instructions from two coequal branches of government, he was compelled to side with his former client.

But House Judiciary Chairman Jerry Nadler, a New York Democrat, told reporters: "We are having the hearing tomorrow and we expect Mr McGahn to show up pursuant to the subpoena."

The blocking maneuver means yet another dispute between Congress and the White House is likely heading for the judicial branch, as the presidency becomes consumed by a forest of litigation.

That may suit Trump, since it will put off the political reckoning that may eventually come and could delay the release of documents he wants to keep secret -- such as his tax returns.

The White House appears to have far stronger arguments in the murky and largely untested area of executive privilege than the President did in his personal suit over his financial records.

But one complication to Trump's arguments lies in the fact that McGahn was made available for hours of testimony already before Robert Mueller -- some of which has already been publicly published in the special counsel's report

If Trump succeeds in thwarting testimony from McGahn it would potentially establish a precedent that Congress could never cross-examine a member of any president's senior staff.

Democrats want to question McGahn on a mound of evidence that Mueller piled up suggesting possible obstruction of justice by the President, including the revelation that he had ordered the then-White House counsel to fire the special counsel himself.

The President got more potentially troubling news with the release Monday of closed-door testimony to Congress by his former personal lawyer Michael Cohen.

Cohen claimed in testimony in March that the President's attorney Jay Sekulow knew that Cohen's claim to Congress that the Trump Tower Moscow project had ended in January 2016 was false.

Sekulow's attorneys said Cohen was trying to blame others and argued that it defied logic for lawmakers to take the word of a man who is currently in jail, partly for lying to Congress.

Trump tries a familiar defense

Mazars, Trump's accountancy firm, will not have to comply with the subpoena for his financial records for another seven days, according to Judge Mehta.

But to stop the handover then, another court will have to step in, possibly as part of the appeals process.

The President reacted to the decision by politicizing it -- painting it as somehow invalid because Mehta had been appointed by his predecessor.

"It's totally the wrong decision by, obviously, an Obama-appointed judge," the President told reporters.

Trump's argument, a familiar one, suggests that he believes justice can be delivered only by a judge who shares his politics, a viewpoint that contravenes basic democratic principles.

The President also resorted to partisan arguments that help him navigate Washington's political wars and please his base.

"The Democrats were very upset with the Mueller report, as perhaps they should be. But, I mean, the country is very happy about it because there was never anything like that."

But one lesson of Monday's ruling is that Trump's personal political arguments and evasions, though serviceable to survive a news cycle, tend to be far less effective in the courts.