President Trump in the Oval Office on Tuesday. (Kevin Dietsch/Pool/Bloomberg News)
Cass R. Sunstein is the Robert Walmsley University Professor at Harvard Law School. From 2009-2012, he served as administrator of the White House Office of Information and Regulatory Affairs. He is the author of several books, including "Impeachment: A Citizen’s Guide."

Since the April release of special counsel Robert Mueller’s report, debate has escalated among Democrats in the House of Representatives over the question of impeachment. A lot of the discussion has focused on political questions. Which party would benefit? Is it a serious problem that impeachment proceedings would be, as Speaker Nancy Pelosi (D-Calif.) has suggested, “divisive”? Is impeachment a criminal or a “political” proceeding?

It certainly isn’t a criminal proceeding, and it has an inescapable political component. But under the Constitution, impeachment is fundamentally a question of law, not politics. If, after assessing the facts, the House concludes that a president — Democratic or Republican — has clearly committed “high crimes and misdemeanors,” then impeachment isn’t optional. In that event, the House has a duty to act, regardless of any potential political fallout.

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Delegates to the Constitutional Convention devoted a great deal of attention to the legal standard — the grounds for impeachment. An early draft of the Constitution referred to “malpractice or neglect of duty.” Alexander Hamilton preferred “mal and corrupt conduct.” James Madison focused on “the incapacity, negligence or perfidy of the chief Magistrate.”

In a late draft, these terms were narrowed to just two grounds: treason and bribery. But Virginia’s George Mason offered a powerful objection, urging that “many great and dangerous offenses” would not be covered. He moved to add the word “maladministration” after “bribery.” In suggesting that word, he was trying to build on the practice in some states, which had used it in their own impeachment provisions.

But Madison thought “maladministration” was “vague” and would effectively make a president’s term subject to the “pleasure of the Senate.” Deferring to Madison, Mason withdrew his proposal and instead suggested “other high crimes and misdemeanors.”

At the time, that phrase had a well-understood meaning. It wasn’t meant as a dodge or a punt. It had a history in England, in the colonies and in the young United States, where it extended beyond crimes to official corruption and serious misuses of power. It was tighter and more specific than “maladministration.” At the same time, it would reach “great and dangerous offenses,” understood as egregious abuses of presidential authority, whether they were a violation of the criminal law.

During the ratification debates, this was repeatedly made clear. For example, abuses of the pardon power would be impeachable. As Madison put it, in describing limits on that power: “If the president be connected in any suspicious manner with any persons, and there be grounds to believe he will shelter himself; the house of representatives can impeach him.”

Violations of rights would also be impeachable. Under the pen name “Cassius,” one Massachusetts commentator wrote: Thus we see that no officer, however exalted, can protect the miscreant, who dares invade the liberties of his country, or countenance in his crimes the impious villain who sacrilegiously attempts to trample upon the rights of freemen.”

The framers and ratifiers didn’t want Congress to play politics with the impeachment mechanism. The House is not permitted to impeach a president because its members despise him personally, abhor his policy judgments or believe he is unfit for office — there’s no constitutional equivalent for the parliamentary no-confidence vote. And the House isn’t authorized to look the other way if a president clearly commits treason, bribery or some other high crime or misdemeanor.

Some cases do fall within a gray area, in which reasonable people can disagree about whether the standard has been met, on the facts or on the law; that’s where the House is allowed not to proceed. But while the founders meant to prohibit politically motivated impeachment, they didn’t contemplate inaction under circumstances involving egregious abuses of power. Against the backdrop of the American Revolution and the Declaration of Independence — which itself reads like articles of impeachment directed against the king — it’s implausible to think that impeachment was understood as optional, or something to forgo if the politics weren’t right.

Some argue that the House can legitimately take account of the political terrain before proceeding to impeachment. For example, my Harvard Law School colleague Laurence H. Tribe contends the House may make and consider a “prognosis of what the Senate might do.” Today, some Democrats suggest the House can decline to consider impeachment proceedings on pragmatic grounds. Impeachment is a political loser; Republicans lost House seats after opening an impeachment inquiry against President Bill Clinton. Or: There’s a presidential election coming up, let the voters decide. Or: Since Republicans control the Senate, and there’s no way they’ll convict an impeached president, what’s the point?

To be sure, nothing in the Constitution’s text explicitly says impeachment is mandatory. But deliberations during the founding period strongly suggest that if the grounds for impeachment are clearly established, the House is not allowed to look the other way. (Tribe comes close to this view, suggesting that if the House did not proceed in such cases, it would be abusing the discretion it has.)

At the Constitutional Convention, the decision to create a powerful president was among the most controversial of all. It threatened to derail the whole project. After the Revolution, the young nation did not want anything like a monarch. One delegate argued that having a president meant the nation would have an elective king. Another complained of “the fetus of monarchy.” John Dickinson, a leading thinker, objected that the proposed constitution would produce an executive “not consistent with a republic.” In response to these concerns, the impeachment mechanism was deemed to be essential. Mason put it this way:

No point is of more importance than that the right of impeachment should be continued. Shall any man be above Justice? Above all shall that man be above it, who can commit the most extensive injustice? . . . Shall the man who has practiced corruption & by that means procured his appoint in the first instance, be suffered to escape punishment?

As the framers and ratifiers made clear, impeachment was a crucial mechanism for protecting the principles for which Americans had fought — for ensuring a republic, not a monarchy. Without the impeachment clause, a president, once in office, would have unchecked power to commit horrific offenses against the Constitution and We the People.

In that light, it would be quite implausible to suggest the House is permitted to stay its hand or to consider politics if a president has committed treason, accepted bribes or trampled on the Bill of Rights.

These are points about the Constitution generally, not about President Trump. But there is no question the Mueller report contains some disturbing findings, above all with respect to obstruction of justice. The House cannot simply ignore those findings.

The report is at pains to say it does not exonerate the president. You could easily read it to suggest its authors did conclude the president obstructed justice — and they declined to state that conclusion only because the Justice Department has said the president cannot be prosecuted, which means he cannot clear his name in court (in the words of the report, “fairness concerns counseled against” announcing that the president committed a crime “when no charges can be brought”).

But the House is hardly required to agree with the Mueller Report (or with others who have leveled charges, serious or otherwise, against the president). Its members have their own constitutional responsibility, which they must exercise in a way that keeps faith with the founding document.

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In 1787, Benjamin Franklin famously reported that the Constitutional Convention had produced a republic, “if you can keep it.” The Constitution’s impeachment clause imposes a solemn obligation on Congress: to keep it.