Suppose that within the next few months, it becomes clear that President Donald Trump has committed impeachable offenses. Does the House of Representatives have discretion to decide whether to impeach him? Or does the Constitution require it to do so?

The simplest answer, and the best, is that the Constitution requires the House to do so.

To avoid political bias, let’s bracket all questions associated with President Trump, put current events to one side, and assume that some future president commits (in the words of the Constitution) “Treason, Bribery, or other high Crimes and Misdemeanors.” Imagine that he has betrayed his country, in a way that constitutes treason, or that he has killed or imprisoned journalists and political enemies (clearly a high crime and misdemeanor, and so an impeachable offense).

The Constitution says that the House of Representatives “shall have the sole Power of Impeachment,” and that the Senate “shall have the sole Power to try all Impeachments.”

In light of the historical background, use of these powers is best regarded as mandatory rather than optional, at least when a president has clearly committed impeachable offenses. To the founding generation, the impeachment provisions were essential parts of the Constitution.

As Virginia’s George Mason put it at the Constitutional Convention, “No point is of more importance than that the right of impeachment should be continued.” (It is worth pausing over that sentence.)

The power of impeachment was designed to ensure that our system would be one of self-government. It gave We the People an ultimate weapon in the event that the president violated the principles embodied in the Declaration of Independence: “A Prince, whose character is marked by every act which may define a Tyrant, is unfit to be the ruler of a free people.”

For this reason, it is wrong to say, as many now do, that the Constitution makes impeachment a political question rather than one of law. On the contrary, the Constitution sets out a legal standard, which establishes a very high bar, and which forbids impeachment on purely political grounds. At the same time, the Constitution specifies what has to happen if the constitutional standard is clearly met.

Suppose that the House of Representatives were entitled to respond to impeachable offenses with a kind of shrug, or with the thought, “he’s doing a great job, so we’ll let it pass,” or with the admission, “sure, he’s a bum, but he’s our bum.”

That would make a mockery of the constitutional plan. It would allow the project of self-government to collapse.

It is exceedingly difficult to read the founding-era debates about impeachment — during the Constitutional Convention and the ratification debates — without concluding that if the president has clearly committed an impeachable offense, the House has a constitutional duty to impeach him.

Some people reject this conclusion. In an impressively detailed and highly illuminating book, Laurence Tribe and Joshua Matz invoke the analogy of the criminal prosecutor. Tribe and Matz rightly note that criminal prosecutors are entitled to exercise discretion. Even if a criminal offense has been committed, prosecutors are allowed to conclude that all things considered, criminal prosecution would not be a good idea.

Tribe and Matz make a plausible argument, but their analogy doesn’t work. Faced with limited budgets and many potential targets, prosecutors must exercise their judgment in order to ensure that the awesome power of the criminal law is used appropriately. By contrast, the House of Representatives is not enforcing the criminal law; it is not threatening anyone with a jail sentence.

Its constitutional obligation is to protect We the People. It is not entitled to look the other way.

This conclusion does not mean that courts are available to ensure that the House does its duty. The Supreme Court has made it clear that impeachment questions are “nonjusticiable,” which means that judges will not resolve them. But even if courts will not get involved, elected officials have a solemn duty to the Constitution, which they are sworn to uphold.

There is one qualification. Although the constitutional test — treason, bribery, or other high crimes and misdemeanors — is far clearer and more concrete than many people think, it does leave some hard cases.

Suppose that a president abridges liberty in some serious way in a time when national security is genuinely threatened — and so violates the Constitution. Because the president’s first job is to protect the nation, reasonable people can disagree about whether such actions make up an impeachable offense. It is fair to say that where the Constitution does not speak unambiguously, members of the House of Representatives are entitled to exercise their judgment.

But if any future president — Democrat or Republican — commits what is clearly an impeachable offense, the House is obliged, and not merely permitted, to initiate impeachment proceedings. A refusal to do so would be a dereliction of constitutional duty, a violation of the oath of office, and a shameful betrayal of the principles for which the American Revolution was fought.

Cass R. Sunstein is a Bloomberg Opinion columnist