Pablo Martinez Monsivais / AP

In denouncing the impeachment inquiry as an illegitimate exercise and blocking a key witness from testifying before what he described as a “kangaroo court,” President Donald Trump’s actions this week spawn a deeply troubling question: Will Trump next disregard the authority of the judicial branch of government?

This is hardly outside the realm of possibility. After all, Trump is ignoring one of the three co-equal branches of government — the legislative branch — by saying he won’t respect Congress’ Article 1 powers. Why, then, wouldn’t he ignore the courts as well?

This is a president who shows a flagrant contempt for any limits on his executive power, whether formal checks and balances or unwritten rules of decorum and statesmanship. He operates with McCarthy-like petulance and vindictiveness toward those who oppose him, even critics in the Republican Party and governmental entities like the FBI and Department of Justice.

Now, in trying to wave off the powers of Congress, he’s attacking the basic structure that the Founding Fathers put in place to ensure a sensible decision-making process and, on the extreme end, to protect the nation against tyranny.

Given his actions, there’s every reason to question whether his next target might be the power of the courts. For a president who disrespects the Article 1 powers, which are very clearly defined, it wouldn’t be much of a stretch to try to operate beyond the reach of the courts as well.

Let’s be clear, too: There’s nothing illegitimate about the impeachment inquiry. White House lawyer Pat Cipollone claims that’s the case because the House hasn’t formally voted to launch the probe, but that’s a bogus argument. Not only is there no requirement for a vote to initiate impeachment proceedings, but a vote is a foregone conclusion given the Democratic majority in the House.

There’s also no question whether there are legitimate grounds for the probe. The White House’s own notes from Trump’s July conversation with Ukrainian President Volodymyr Zelenskiy show that he asked Zelenskiy to investigate Joe Biden and to work in tandem with Attorney General William Barr and Trump’s personal lawyer, Rudy Giuliani. And it’s clear desperately needed military aid for Ukraine was being withheld until Zelenskiy played ball.

So the Trump administration is the only entity acting unconstitutionally here.

That being the case, it’s wholly irresponsible for Republican leaders to defend the president from the inquiry. Regardless of party affiliation, it’s the duty of members of Congress to hold the executive branch accountable.

If Trump has nothing to hide, then he has nothing to fear. But he fears investigations a great deal, and he hides everything he can. This is the way guilty people act, not innocent ones.

Today, the administration is saying the executive branch doesn’t have to answer to the legislative branch. Tomorrow, what’s to say it won’t also try to place itself above the judicial branch?

Again, that’s not a far-fetched question. Keep in mind Trump’s defense in the New York lawsuit regarding his tax returns, in which his lawyers made broad claims of presidential immunity from criminal investigation — even arguing that Trump’s company and business associates were protected. In an impassioned ruling this week, a federal judge called those arguments “repugnant” and said they would “constitute an overreach of executive power.”

As the judge clearly understood, Trump’s views on the scope of his authority are alarming.

This is the very scenario for which the nation’s founders established the brilliant three-branch conception, designed to protect Americans from the subjugation they endured under a British monarchy that could unilaterally create laws, administer them and enforce them.

Trump’s actions put that protection in deep peril.