President Trump really, really doesn’t like the fact that congressional committees are investigating him. On Wednesday, he was so mad that he stormed out of a meeting with House Speaker Nancy Pelosi about critically needed infrastructure legislation after only three minutes, much like the proverbial boy who takes the football home if he loses a disputed call.

Trump’s tantrum reflects the fact that the American people and their representatives are getting closer to seeing behind the curtain of secrecy that Trump has wrapped around his financial dealings — even where they implicate serious conflicts of interest prohibited by the Constitution’s ban on presidents accepting “emoluments,” or anything of value, from foreign or domestic government officials.

On Monday and Wednesday, federal judges in D.C. and New York rejected Trump’s efforts to block subpoenas aimed at uncovering his financial records. Also on Wednesday, the New York Legislature cleared the way to disclosing Trump’s state tax returns.

What President Trump objects to so strenuously is nothing more than what the framers of our Constitution demanded: a system of accountability. The framers intentionally designed our government so that exactly this would happen. They called it checks and balances, believing that the best way to rein in abuses of power is to divide authority among the three branches of the federal government, as well as among the federal and state governments, so that the different branches will work to keep each other in line.

During Trump’s first two years in office, the framers’ plan was largely foiled by one-party rule. Republicans controlled both houses of Congress and the majority of the state legislatures, and a majority of the Supreme Court’s justices were Republican-appointees. And Republicans have shown little willingness to check this president. To date, Rep. Justin Amash is the only Republican member of Congress who has called out the president for the obstruction of justice so plainly detailed in the Mueller report. But in the midterms, the American people elected enough Democrats to flip control of the House of Representatives — and we are now seeing the separation of powers back in action. 

Trump is none too pleased. His first response was to stonewall on all subpoenas. He argued that House committees have no authority to investigate except where their investigation is tied to a specific piece of legislation. But that argument is dead wrong, and the federal courts have properly and resoundingly rejected it.

To do its job, Congress has to have broad investigative authority. It has to understand the scope of a problem before it can come up with a solution. Thus, when Facebook failed to protect the privacy of its users, Congress called in Mark Zuckerberg. When four Americans, including Ambassador J. Christopher Stevens, were killed in Benghazi, Congress held hearings to review what happened. In the 1970s, when it appeared that the CIA and FBI were spying on civil rights and anti-war organizations, a Senate committee conducted a massive investigation. And when James Comey was fired, Congress called him in to testify.

None of these hearings was tied to a specific bill; they were designed to understand a problem in order to determine whether a legislative response was called for. 

Thus, as U.S. District Judge Amit Mehta explained in his ruling Monday rejecting Trump’s effort to block a subpoena of his financial records, the courts have long ruled that Congress has very broad authority to conduct investigations. First, it can investigate any subject as to which it might legislate, whether it ever in fact passes or even introduces legislation. Accordingly, the Supreme Court has said, “the scope of the power of inquiry . . . is as penetrating and far-reaching as the potential power to enact and appropriate under the Constitution.”

And second, it has an “informing” function, which authorizes it to, in the Supreme Court’s words, “inquire into and publicize corruption, maladministration or inefficiency in agencies of the Government.” The Supreme Court has cited Woodrow Wilson for the proposition that “it is the proper duty of a representative body to look diligently into every affair of government and to talk much about what it sees. It is meant to be the eyes and the voice, and to embody the wisdom and will of its constituents.”

These authorities plainly cover investigations of Trump’s efforts to obstruct the Mueller investigation, potential conflicts of interest arising out of his past and present financial dealings, and his compliance — or lack thereof — with the tax code. So if the courts continue to do their job, Trump should be required to disclose much of what he has fought so long to keep from the public’s eyes — and that will then allow our representatives, and the people themselves, to decide on an appropriate response.

The ACLU, the nation’s oldest and largest constitutional rights organization, has always been committed to transparency, accountability, and checks and balances, precisely because we agree with the framers that these procedures safeguard liberty and constrain the abuse of government power. Since Trump has come into office, we’ve turned to the courts repeatedly to protect women’s reproductive rights, immigrants’ rights to due process, citizens’ voting rights, and everyone’s rights to privacy and liberty. The courts have played a critical part in maintaining the rule of law in the face of Trump’s excesses.

But we cannot rely exclusively on judges. Congress has an important checking function as well. And that can only operate if the president abides by basic norms of our Constitution — including that Congress has broad authority to investigate suspected abuse by the President himself.