Nancy Pelosi has made her position clear: She is not budging from her opposition to impeachment. The speaker of the House considers those who advocate for impeachment proceedings to be naive political extremists, folks who would help get Donald Trump reelected by insisting on a useless pose of ideological purity. Her leadership of the Democratic caucus consists, in no small part, of keeping people who favor impeaching President Trump in check. She is a realist, a grown-up.

There’s only one problem: Her case against impeachment is incoherent.

Pelosi has made a number of arguments. Donald Trump, she says, is “not worth it.” Impeachment would be “the easy way out.” Trump “wants to be impeached so he can be exonerated by the Senate”—and beginning proceedings would be a political gift to him.

But Pelosi acknowledges, notwithstanding such dismissive rhetoric, that Trump is “engaged in a criminal coverup” and that his actions are “villainous to the Constitution.” In fact, she says, she wants to see him in prison.

For all the different ways Pelosi has made her case, an implicit principle underlies her argument: Yes, the president’s conduct is egregious, criminal even, but that egregious criminality does not require an impeachment or even the opening of an impeachment inquiry. Impeachment, in her view, is a constitutional tool the House is never required to use, an option, not a command. Consequently, the House’s decision not to impeach or to begin an inquiry is not a comment on whether or not impeachment is merited; Pelosi’s comments that Trump’s behavior is “lawless” and a “gross abuse of the power of the presidency” suggest that she believes it would be merited. In her view, the question of the merits of impeachment—that is, whether the president has committed “high crimes and misdemeanors”—is a threshold judgment only.

Let’s take this position seriously for a moment and consider a few hypotheticals:

Imagine that instead of firing the FBI director in a fit of pique over the director’s refusal to state publicly that the president is not under investigation and to scrap a probe into the president’s former national security adviser, the president had ordered a drone strike on the FBI director’s house.

Or imagine that the president had repeatedly ordered the Secret Service to abduct underage girls to be brought into the Oval Office, where he had assaulted them. Imagine that he had threatened the victims’ families with arrest and prosecution if their children refused his advances. Imagine he also provided gifts to families that remained quiet, using funds appropriated by Congress for other purposes.

Or imagine that the president announced that he would preemptively pardon any law enforcement officer accused of killing a black person in the line of duty, no matter the circumstances. (This last example is adapted from a hypothetical posed by Charles Black in 1974.)

These scenarios are outlandish. But that’s the point. They fulfill all of the conditions that various scholars describe as necessary to constitute an impeachable office. They all obviously meet the criteria for “high crimes and misdemeanors” for which a president may be impeached under the Constitution: They involve abuses of power in violation of the president’s obligations to “take care that the laws be faithfully executed” and to “preserve, protect, and defend the Constitution.” Some are criminal, some are not, but all are vile and, as such, beyond any plausible defense.

If the president had committed any of the acts described above, would Pelosi really argue that a member of Congress who had sworn an oath to “support and defend the Constitution of the United States” and to “well and faithfully discharge the duties of [their] office” might consider impeachment an option but not a requirement? Would she regard the House of Representatives as having no obligation to impeach him, or at the very least to begin an inquiry, irrespective of the political benefits of doing so? Would she regard any obligation as depending on whether the Senate would likely convict or whether the president might somehow benefit politically from the confrontation? Would she care if he wanted to be impeached under such circumstances? Would she suggest that he wasn’t worth impeachment?

Perhaps there is some politician who, faced with the conduct hypothesized above, would take the view that the House still does not have an obligation to impeach. Perhaps there is some politician who would elevate the discretionary political components of the impeachment power over all of their substantive legal content and ask only whether impeachment would be politically advantageous—boiling down the duty to “support and defend the Constitution” to a polling exercise.

I actually doubt that Nancy Pelosi is this politician. I think she, like the rest of us, would recoil in horror under such circumstances and regard impeachment as required—even if the president’s polling numbers were holding up well. If that’s right, then it means that there is some point at which the president’s conduct is so egregious that the House has no choice under the Constitution but to begin impeachment proceedings. Everything else is just haggling over the price. The only remaining question is where one draws the line between conduct that is impeachable but does not mandate impeachment and conduct that is so bad that impeachment becomes a constitutional obligation.

This means that the issue before Nancy Pelosi today, in the nonhypothetical world in which we live, is whether the conduct described in the Mueller report, and in which the president has engaged publicly for the past two years, does or does not cross that line. Pelosi’s actions so far indicate that she does not think Trump’s actions cross it. She has hinted as much: Impeachment “has to be about the truth and the facts to take you to whatever decision has to be there,” she told Fareed Zakaria recently. “It should by no means be done politically.”

One can certainly make this judgment. But in making it, one has to at least acknowledge that the refusal to begin impeachment proceedings is, in fact, a judgment on the merits of the potentially impeachable offense. It’s a judgment that the president’s conduct, while bad, is not that bad. If that is the judgment Pelosi has made, she should stand behind it.