In the alarming here and now of the Trump Presidency, the decision by House Democrats to move ahead with an impeachment inquiry would seem to be a positive step for American democracy. During the Constitutional Convention, in the summer of 1787, James Madison argued that an impeachment clause was necessary in order to guard against the potential “incapacity, negligence or perfidy” of a President and to prevent the perversion of the office “into a scheme of peculation or oppression.” Another dangerous possibility, according to Madison, was that the President “might betray his trust to foreign powers.”

Even if no new information emerges, the basis of a credible impeachment case, very much along the lines of Madison’s fears, has already been laid out against Trump. Based on an anonymous whistle-blower’s complaint to the intelligence community’s inspector general, and also according to a summary of a July phone call between Donald Trump and Volodymyr Zelensky, the President of Ukraine, which is at the heart of the complaint, it appears that Trump pressured Zelensky to investigate a political adversary as a “favor,” implied that military assistance was contingent upon coöperation, and instructed the Ukrainian leader to work with his personal lawyer, Rudy Giuliani, and Attorney General William Barr on the effort. Furthermore, there’s evidence that other officials in the White House took part in a possible coverup.

On Tuesday, when House Speaker Nancy Pelosi announced the beginning of impeachment proceedings, she invoked the nation’s founding ideals—and the need to defend and protect them. “In the darkest days of the American Revolution, Thomas Paine wrote, ‘The times have found us.’ The times found them to fight for and establish our democracy,” Pelosi said. “The times have found us today not to place ourselves in the same category of greatness as our Founders but to place us in the urgency of protecting and defending our Constitution from all enemies, foreign and domestic.”

Pelosi’s defense of impeachment befit the seriousness of the allegations against Trump. But the partisan animus and uncompromising, ruthless tactics that define our politics today make this a delicate moment for American democracy. Norms that have long shaped the governing process have been shunted aside in the Trump era. In this polarized environment, even the proper use of impeachment could lead to the future weaponizing of the process, particularly by Republicans. Impeachment could prove both necessary to safeguard the Republic, as Pelosi asserted, and profoundly dangerous for its future.

The framers labored over the language of the impeachment clause, wanting to insure that it was broad enough to act as a bulwark against serious abuses of public trust by the executive but that it was not so vague as to, essentially, leave the Presidency at the mercy of Congress—or, as one initial skeptic of impeachment, Gouverneur Morris, who wrote the Preamble to the Constitution, put it, a “tool of a faction.” The catalogue of offenses that the Founders settled on included treason, bribery, and the critical phrase for Trump’s case, “high crimes and misdemeanors,” the meaning of which continues to be a subject of fierce debate.

Pelosi has been especially cautious about impeachment. She stubbornly held the line during the special counsel Robert Mueller’s investigation, despite consistent pressure from the Party’s restive left wing. Her motivation was the need to protect vulnerable moderates in her party, whose victories in districts won by Trump in 2016 had allowed the Democrats to retake the House in the midterm elections. But Pelosi’s deliberation was also appropriate, given the long-term repercussions of impeachment, particularly in the age of Trump.

The unrestrained partisan warfare that has characterized the Trump Presidency did not begin with him. The Republican drive to impeach President Clinton, in 1998, might, in fact, be seen as the true beginning of the escalation. A more recent example is the way Republicans, under the direction of Senate Majority Leader Mitch McConnell, refused even to consider President Obama’s Supreme Court nominee Merrick Garland. But the erosion of core democratic norms and institutions has accelerated under Trump, as he has questioned the legitimacy of electoral results, undermined the machinery of government, and led a sustained attack on the media.

These are the hallmarks of autocratic regimes around the world, but equally worrisome, perhaps, is the simultaneous collapse of comity and restraint in the governing of our nation. In addition to the initiation of impeachment proceedings, the past year of the Trump Presidency has also included the longest government shutdown in U.S. history—thirty-five days—and the Administration’s declaration of a national emergency so that it could circumvent congressional approval in the funding of a border wall.

Elsewhere in the world, similar patterns of polarization and reprisal have ultimately led to the collapse of democracies. In the bracing book “How Democracies Die,” Steven Levitsky and Daniel Ziblatt, who are professors of government at Harvard, trace many of the worrisome patterns of the Trump Presidency and outline the ratcheting of consequences that has ultimately led to failures of democracies in other countries:

The erosion of mutual toleration may motivate politicians to deploy their institutional powers as broadly as they can get away with. When parties view one another as mortal enemies, the stakes of political competition heighten dramatically. Losing ceases to be a routine and accepted part of the political process and instead becomes a full-blown catastrophe. When the perceived cost of losing is sufficiently high, politicians will be tempted to abandon forbearance. Acts of constitutional hardball may then in turn further undermine mutual toleration, reinforcing beliefs that our rivals pose a dangerous threat. The result is politics without guardrails. . . .

Among a number of historical examples, Levitsky and Ziblatt examine what happened in Chile after the leftist candidate Salvador Allende ascended to the Presidency, in 1970, in the face of intense opposition from moderate and right-wing opponents. They argue that the pitched partisan conflict that followed between Allende and his allies, who sought to implement his radical socialist vision for the country, and his equally committed opponents, who controlled the National Congress, created the conditions that ultimately led to a military coup, in 1973. “Politics without guardrails killed Chilean democracy,” Levitsky and Ziblatt write. Modern-day Hungary presents another frightening scenario, in which Viktor Orbán, the populist, nativist leader elected in 2010, has been able to marginalize his opposition—both in the parliament and in the press—taking advantage of an overwhelming political majority to overhaul the country’s constitution and gerrymander voting districts to solidify his party’s hold on power.