The title and timing of “To End a Presidency: The Power of Impeachment”might lead the unwary reader to expect a polemic. But no. Inside these covers is a learned, judicious, and surprisingly cautious study of the impeachment power by Laurence Tribe, who ranks high among America’s leading constitutional scholars, and his former student, Joshua Matz. Their message: Impeachment is a very, very dangerous thing. Proceed with caution.

Worse: “Well-justified calls to impeach the president can simultaneously empower him, harm his political opponents, and make his removal from office less likely … Because removing a truly determined tyrant may unleash havoc, the risks of impeaching a president are apt to be most extreme precisely when ending his tenure is most necessary.”

By perverse contrast: “An impeachment may be most likely to succeed in Congress when other, less extreme measures are also most viable.”

We live in a time of what the authors call “impeachment talk.” They note that only five presidents faced credible impeachment threats up until the year 1992: Andrew Jackson, John Tyler, Andrew Johnson, Richard Nixon, and Ronald Reagan. By contrast, every president since 1992 has faced a credible impeachment threat—and, of course, Bill Clinton actually was impeached.

The authors make a cynical but shrewd observation about post-1992 impeachment talk: It is often stirred not by the president’s opponents, but by the president’s supporters, as a way to sustain political engagement between elections.

Many conservatives were thrilled in March 2006 when Democratic Senator Russell Feingold proposed censuring [George W.] Bush for warrantless domestic surveillance. The president’s public approval ratings had collapsed.

With midterm elections on the horizon, Republicans feared losing control of Congress. What better way to fire up the base than to warn that Democrats would impeach Bush if they prevailed? “This is such a gift,” Rush Limbaugh told listeners. The Wall Street Journal ran an op-ed entitled, “The Impeachment Agenda,” which the Republican National Committee shared with 15 million supporters … As reporter David Kirkpatrick observed at the time, “in playing up the impeachment threat, conservatives have forged an alliance of sorts with the most liberal wing of the Democratic Party.”

The script would be reversed in the Obama presidency, and for exactly the same reasons. Despite the extreme abuse hurled his way, Barack Obama was never in danger of being impeached. But his supporters believed he was, and that belief served as an important political resource to Democrats as Republicans gained control of Congress and many state legislatures starting in 2010.

Since the 1990s, we have entered the age of the permanent campaign, with permanent fundraising, permanent partisanship—and, in tandem, permanent impeachment hearings. Americans speak more roughly about their presidents and, precisely because they do, often do not take their own words seriously. How often was Obama called a dictator? And yet people who used that language most effectively acknowledged afterward that they never meant it to be taken seriously.

Perhaps they imagine that concerned language about Trump should be interpreted the same way, as just an over-emphatic expression of ordinary political difference. As Americans talk more about impeachment, they seem to care less. The idea that a president could be a threat to the democratic system as a whole, a threat to be heeded seriously by people of all points of view, has faded—perhaps because, for so many Americans, faith in that system has faded, too. The authors write:

Many Americans who voted for Trump view themselves as belonging to a victimized, disenfranchised class that has finally discovered its champion. For some of them, Trump’s appeal is less what he will accomplish programmatically than whom he will attack personally. Were Trump removed from office by political elites in Washington, DC—even based on clear evidence that he had grossly abused power—some of his supporters would surely view the decision as an illegitimate coup. Indeed, some right-wing leaders have already denounced the campaign to remove Trump as a prelude to civil war. This rhetoric, too, escapes reality and indulges pernicious tendencies toward apocalyptic thinking about the impeachment power. 

Tribe and Matz regard Trump as bad news: bad for the political system overall, and bad for their own specific liberal policy preferences. And yet the most remarkable thing about To End a Presidency is the spirit of moderation they bring to their vision of how those harms should be mitigated.

If there is one central piece of advice that Tribe and Matz would impart, it is this: Impeachment is a political question, not a legal one. Do not imagine that even if you could perfectly know what the Framers meant by “high Crimes and Misdemeanors”—the Constitution’s enigmatic catch-all grounds for impeachment after Treason and Bribery—that you could solve the problem of when or whether to impeach. As they tell it, impeachment may be unwise even when justified. “Under most circumstances, removing the president from office this way is bound to be divisive and disheartening,” they write. “Even when taking that step is fully justified, the price may be higher and the benefits more modest than some would envision.”

So what is to be done? Their answer, in a word, is politics. Grand visions of putting on trial a corrupt or tyrannical or treasonable president “falsely devalue other ways of defending democracy, including popular activism, local and state political engagement, filing lawsuits, donating to civil rights groups, and undertaking private ventures in the public interest.”

The Republicans who failed to remove Andrew Johnson in 1868 did chasten him to cease sabotaging black civil and voting rights in the final year of his presidency. They then elected a replacement more committed to Reconstruction’s goals, Ulysses S. Grant. This is the model they urge the Americans of today to emulate as long as they can. And if that point is ever passed—if evidence reveals a danger so urgent, imminent, and overwhelming that impeachment becomes inevitable—Tribe and Matz plead for limiting the goals of any impeachment process as narrowly as possible in order to achieve the broadest possible coalition in support.

Trump will not be removed from power unless a large number of Republicans and independents, along with Democrats, agree that he has to go. But the truth is that most of those voters don’t believe the sky is falling. Nor are they automatically inclined to view impeachment as an appropriate sanction for Trump — even when they disagree with him or find him embarrassing. In engaging with those voters, urging impeachment and suggesting that it will undo all of his major decisions could prove counter-persuasive. The clear-thinking message of “To End a Presidency” deserves the widest audience. It is a hopeful summons to defend an imperiled democracy.

David Frum is a senior editor at The Atlantic. In 2001–02, he was a speechwriter for President George W. Bush.