On Wednesday, the House Judiciary Committee voted to hold Trump attorney general William Barr in contempt of Congress for refusing to turn over the unredacted Mueller report in response to a congressional subpoena. A day earlier, Treasury Secretary Steve Mnuchin announced that he would not turn over the president's tax returns to the House Ways & Means Committee, despite the existence of a federal statute that legally requires him to do so upon request. If committee chair Richard Neal decides to go ahead and subpoena the returns, Mnuchin will presumably respond with some other iteration of "nah," too.

This is not the first time Congress has rebuked a sitting attorney general in this manner. (In 2012, House Republicans held then-attorney general Eric Holder in contempt for allegedly providing misleading testimony to the Judiciary Committee; most Democrats walked off the House floor in protest.) But together, Barr's and Mnuchin's decisions indicate that this administration plans to dismiss every attempt at oversight as an illegitimate, politically-motivated stunt. In a statement about Trump's assertion of executive privilege over Mueller's report—ostensibly the legal rationale excusing Barr's noncompliance—White House press secretary Sarah Sanders offered what is sure to become a common refrain.

The American people see through Chairman Nadler's desperate ploy to distract from the President's historically successful agenda and our booming economy. Neither the White House nor Attorney General Barr will comply with Chairman Nadler's unlawful and reckless demands. ... It is sad that Chairman Nadler is only interested in pandering to the press and pleasing his radical left constituency. The American people deserve a Congress that is focused on solving real problems like the crisis at the border, high prescription drug prices, our country's crumbling infrastructure, and so much more.

An across-the-board stonewalling strategy places what is supposed to be a basic element of American tripartite democracy—the checks and balances each branch imposes on the others—in serious jeopardy. "The Trump administration's refusal to cooperate represents a challenge to the very idea that Congress provides oversight of the president," Harvard Law School constitutional law professor Noah Feldman told me. "Anyone elected president, by definition, has a lot of power. Unless someone is in a position to provide oversight, the president functions as above the law."

If the full House eventually votes to hold Barr or Mnuchin in contempt, Nadler and Neal would have two realistic paths available to them. (A third—asking federal prosecutors to pursue criminal charges against sitting Trump Cabinet officials, including the head of the Department of Justice—seems exceedingly unlikely.) First, and most conventionally, legislators can ask a court to intervene and order a recalcitrant subpoena recipient to hand over any sought-after materials. This, in itself, is a check and balance: recruiting a third branch of government to settle a dispute between the other two.

In the alternative, Congress can enforce its own contempt findings by ordering the House sergeant-at-arms to arrest an uncooperative witness who, as the Supreme Court put it in a landmark 1935 opinion, "obstruct[s] the performance of the duties of the legislature." Lawmakers haven't invoked this "inherent contempt power" in nearly a century, notes Larry Tribe, Feldman's colleague at Harvard Law School, which can make it sound a little outlandish to modern ears. "But you have to realize we are not living in normal times," he says. "In confronting this kind of unrestrained White House occupant, Congress might have to reach back into its toolbox."

The problem with relying on the courts here, notes Feldman, is that exhausting a lengthy appeals process takes time. With the 2020 election only 18 months away, Trump has a powerful incentive to postpone any bombshell revelations about his conduct until after he's finished making his pitch to voters for a second term. For anyone who needs to drag their feet, involving the morass that is the federal court system is a fantastic method of doing it.

Tribe is a little more optimistic, pointing out that judges managed to resolve Nixon's claims of executive privilege over the Oval Office tapes in a matter of months. "Courts know how to expedite things," he says. And in the meantime, administration officials are not the only ones from whom Congress can solicit oversight-related information. Even if the White House ignores subpoenas of its members, for example, there is little it can do about subpoenas to Deutsche Bank, Capital One, and any other third parties from which lawmakers might demand information. "They are going to comply, and tell the president to go to hell," Tribe adds.

Tribe stopped short of declaring this to be a full-blown constitutional crisis, although he noted that Trump appears to be doing his level best to create one. Only if the administration were to defy an eventual court order might such apocalyptic language be in order. "If the system responds as it is supposed to respond—if the courts push back and he complies—things will be on track," Tribe tells me. "But we won't really know until we see how the courts respond."

Feldman agrees. "My working definition of that term is when you have two branches of government staring each other down, and no one knows what happens next," he says. This is a high-stakes conflict and makes for great law school exam fodder, but after 250 fraught years of constitutional democracy, it is at least a familiar-enough fact pattern. "Now, if Congress sends the sergeant-at-arms down Pennsylvania Avenue to go into the Department of Justice and arrest the attorney general, and FBI agents line up on the other side?" That, Feldman believes, would be a true constitutional crisis. And we're not there—at least, not yet.