President Trump had the legal authority to fire James B. Comey on Tuesday, and he originally argued that doing so was necessary because, he said, Mr. Comey committed serious violations of law-enforcement norms during his investigation of Hillary Clinton last year.
But critics say that Mr. Trump has himself violated a longstanding norm of American politics: the unwritten rule that presidents should not remove the F.B.I. director without extreme justification, in order to avoid politicizing law enforcement. Before Tuesday, only one F.B.I. director had ever been fired, and that was after an investigation found he had committed egregious ethical violations — and after he refused entreaties to resign.
That has left many wondering how to evaluate Mr. Trump’s actions. Was his firing of Mr. Comey a necessary decision? Merely a minor disturbance of political etiquette? A catastrophic blow to democracy?
Political scientists who study democracy and authoritarianism know the answers will be long debated. The true significance of Mr. Comey’s firing, they say, is that it presents a kind of stress test for American democratic institutions. In unhealthy systems, norm violations can spiral into tit-for-tat retaliation, ultimately tearing democracies apart. But in strong democracies, institutions will step in to enforce vital norms, preventing escalation and protecting the democratic system.
Norms about political behavior and power serve as “soft guardrails for democracy,” said Steven Levitsky, a professor at Harvard who studies authoritarianism.
In a healthy democratic system, when politicians violate important norms, other institutions push back, ensuring that the violators pay a hefty price and the guardrails are preserved for another day.
But in collapsing democracies, the opposite happens. Instead of banding together to protect democratic norms, warring parties take violations by their opponents as justification for breaking other norms in response. “It’s a process of escalation that often begins with minor stuff and ends with coups,” Mr. Levitsky said.
Of course, people don’t necessarily engage in that escalation with the intent of consolidating authoritarian power. But without the stability and protections those “guardrails” offer, normal democratic competition can spin into a partisan battle that ultimately tears democracies apart.
“That kind of partisan fight to the death is what killed democracy in Spain in the 1930s, it’s what killed democracy in Brazil in the 1960s, it’s what killed democracy in Chile with Allende in the early 1970s,” Mr. Levitsky said, referring to that country’s former president, Salvador Allende. The regimes that took over in those countries were right wing, but leftist authoritarians like Venezuela’s Hugo Chávez have followed a similar path.
Sheri Berman, a political-science professor at Barnard College, has observed that process in her study of democratic backsliding in countries like Hungary and Turkey. “There was a gradual evisceration of democracy,” she said, leaving those countries with the “trappings” of democracy, like elections and political parties, but not the substance.
American democracy is far from that terminal state, experts say. But they see the Comey firing as the latest in a string of norm violations, by Mr. Trump as well as others, that have been slowly escalating — and as a test of whether today’s polarized political system will halt that escalation or accelerate it.
Mr. Trump has a long history of violating political norms, Mr. Levitsky said.
For example, “it was once a norm that you don’t insult your opponent’s wife’s physical appearance,” he said, referring to Mr. Trump’s derogatory tweet about Heidi Cruz, the wife of his primary opponent Ted Cruz.
And even before the primary campaign began, Mr. Trump first came to political prominence through the so-called birther movement, which asserted Barack Obama might have forged his birth certificate and was not born in the United States (He was).
Though many people criticized such behavior, Mr. Trump’s supporters applauded it as evidence of his willingness to “say what he is really thinking,” even if that meant challenging elites.
Mr. Trump’s populist stance meant that violating norms was a useful political tool. “If you are a politician or a voter or activist who supports a populist project, then norm violation is a ‘good’ thing,” Mr. Levitsky said. “You’re bringing down a corrupt system.”
He ticked off examples from his research of populists who had employed that strategy: Juan Perón in Argentina; Alberto Fujimori in Peru.
Violations of minor norms of political civility are distressing but not necessarily serious. However, when politicians repeatedly violate core norms, that can be much more damaging.
The norm against American presidents firing their F.B.I. directors may fall into the latter category, experts say. It is part of a broader norm of restraint — of politicians not going all the way to the limits of their legal power.
“A key to making democracy work in the long run is that the parties recognize that institutions shouldn’t be weaponized,” Mr. Levitsky said. “You don’t use your control over institutions to the max.”
That norm may already have been eroding, for example, in President Obama’s expanded use of executive orders to circumvent an uncooperative Congress. And the Justice Department explained its recommendation to dismiss Mr. Comey by saying he had violated norms while investigating Hillary Clinton’s use of a private email server. (Mr. Trump later said in an interview with NBC that he would have fired Mr. Comey regardless of the Justice Department’s recommendations.)
“Studying democratic breakdown around the world, what is clear is that it’s much more about the underlying informal norms than about the formal rules,” Mr. Levitsky said. “That is what Americans need to understand. The underlying informal norms are essential. And Trump just broke one.”
Robert Mickey, a professor of political science at the University of Michigan, pointed out that even after it was found that Williams Sessions, the F.B.I. director, had broken ethics rules, President Clinton first sought a resignation before firing him.
“Clinton was trying to bend over backwards to avoid firing this guy who’d just been investigated by the other party! That’s a nice illustration of this norm of not using your powers to the hilt,” Mr. Mickey said.
Those inclined to panic over Mr. Comey’s firing may be relieved to hear that previous presidents have violated core democratic norms and the republic is still standing.
President Nixon, for example, ousted multiple Justice Department officials in an episode that came to be known as the Saturday Night Massacre.
And President Franklin Delano Roosevelt ran for a third term and then a fourth term in office — not illegal, but unprecedented — and sought to pack the Supreme Court with friendly nominees.
But those norm violations triggered a strong backlash from other institutions of the American government, unlike in countries that collapsed into authoritarianism.
And so the main significance of Mr. Trump’s firing of Mr. Comey, some academics say, may be as a test of whether today’s institutions are strong enough to maintain limits on presidential power and ensure that law enforcement is protected from political influence, a hallmark of democracy.
Partisan polarization may make that harder. Since 1980, Republicans and Democrats have been reporting increasingly negative opinions of each other, and partisanship has become a kind of tribal identity that many people see as a representation of who they are and a team to support.
As a result, politicians now have tremendous incentive to support their party at all costs in order to demonstrate proper partisan loyalties.
Republicans who push back against Mr. Trump’s norm violations, Mr. Levitsky and Mr. Mickey said, may face punishment from voters loyal to Mr. Trump.
Partisanship may also give Democratic politicians an incentive to escalate.
Partisanship and Mr. Trump’s norm-breaking, polarizing presidency have stirred anger among the Democratic base. But Mr. Levitsky was careful to distinguish between ordinary heated opposition and claims that Mr. Trump is “not my president,” or is unfit for office: “They must understand for the sake of democracy that that kind of step, rejecting the legitimacy of Trump’s presidency, is another important step forward in that escalation.”
A more severe form of that kind of polarization fueled the rise of Mr. Chávez, who ultimately transformed Venezuela, a longstanding democracy, into an authoritarian regime.
Mr. Mickey, however, sees hopeful signs in the early response to Mr. Comey’s firing. He pointed out that in the hours after his firing was announced, several Republican lawmakers issued statements criticizing Mr. Trump’s actions.
“I feel heartened by the elite establishment freakout,” he said. “I wouldn’t be too pessimistic about some spiral into destruction.”