Rudy Giuliani is the most glaring example. A former New York mayor serving as the president’s private lawyer, Giuliani conducted foreign policy in Ukraine on Trump’s behalf without enduring the confirmation process or even going under contract with the U.S. government. And he did it in ways that were at odds with official American policy, as numerous career diplomats and national-security officials testified in the House impeachment proceedings.

Trump has also refused to fill crucial vacancies within the executive branch—leaving the Federal Election Commission unable to take any enforcement actions for violations of federal campaign laws in the lead-up to the 2020 election, for example. Moreover, rather than making formal appointments and soliciting the Senate’s advice and consent, as the Constitution requires for top-tier officials, Trump has installed temporary appointees in key posts in his administration—including giving Mick Mulvaney the dual titles of acting White House chief of staff and acting director of the Consumer Financial Protection Bureau. Of course, Trump isn’t the first president to appoint acting officials. But he has explicitly defended his extensive use of this stopgap tool because of the flexibility it gives him.

In short, Philbin is badly mistaken if he thinks that, after the trial is over, Congress can counteract Trump’s worst instincts by holding up his nominees.

The last option Philbin listed was impeachment itself. Trump and his allies have deceived themselves and their supporters that impeachment—the ultimate guard against presidential excess—is nothing more than a cynical instrument of partisan warfare. Senator Joni Ernst, a Republican from Iowa, announced yesterday that Trump’s impeachment over the Ukraine scandal opens the door to impeachment of a future President Joe Biden over activity by him and his son in the same country.

Worse still, Trump has set a precedent that compliance with investigations by the legislative branch would diminish his own power, and is therefore purely optional. Impeachment cannot work if Congress lacks the basic facts bearing on the grounds for impeachment. This president has roundly defied subpoenas for witnesses and documentary evidence, and he has suffered no adverse consequences for doing so. Oversight of the sprawling and powerful executive branch is a vital function of Congress, yet why would any future president of either party comply with politically damaging congressional investigations if Trump got away with evading them with impunity?

All told, Philbin’s list of Congress’s remaining levers of presidential oversight is antiquated—as a Trump lawyer, of all people, should know—and in fact provides a point-by-point argument for why the constitutional stakes are now so high.