President Trump speaks in the Oval Office. (Jabin Botsford/The Washington Post)

Matthew Miller was director of the Justice Department’s public affairs office from 2009 to 2011.

Since President Richard Nixon forced the resignations of the attorney general and deputy attorney general in 1973 in protest to his order to dismiss a special prosecutor investigating the White House, all senior Justice Department officials have known that there could come a time when they would stand before history and face a defining test: Would they have the courage to say no to a president determined to subvert the bedrock independence of federal law enforcement?

On Tuesday, Attorney General Jeff Sessions and Deputy Attorney General Rod J. Rosenstein failed this test. By providing President Trump with the cover to fire FBI Director James B. Comey, they betrayed the Justice Department’s long-standing tradition of independence. In doing so, they sent a message to every career prosecutor and investigator working beneath them that they put the president’s personal and political interests ahead of the department’s integrity.

(Adriana Usero/The Washington Post)

According to the White House’s initial version of events, Comey’s firing was initiated by Rosenstein, who decided — of his own accord, during his first two weeks on the job — to launch a review of the FBI director, concluded that review and made a determination that Comey had to go. This version was implausible, and the White House offered a new accounting today.

In this revised version, Trump gradually lost confidence in Comey, while Sessions and Rosenstein independently came to the same conclusion, which they shared with the president after it “came up” at an unrelated meeting on Monday. The president then supposedly requested an explanation in writing, which Rosenstein supplied on Tuesday.

But nothing about Rosenstein’s memo comports with a typical Justice Department finding. It quotes extensively from public comments made by former department officials, in a manner more akin to a political research document than an official review. It provides no citations of the U.S. Attorneys’ Manual — the governing document for all Justice Department officials. And despite making judgments about Comey’s conduct, there is no indication that Rosenstein actually asked Comey for his version of events.

The timing here is also highly suspect. As multiple media outlets have reported, Comey asked Rosenstein for additional resources for the Russia investigation just last week. Comey was also set to testify about that probe on Capitol Hill on Thursday.

Furthermore, the Justice Department’s inspector general was already reviewing Comey’s conduct, and Comey himself disclosed that he had been interviewed as part of the investigation and supplied facts not yet in the public record. But rather than wait for that investigation to run its course, Trump, Sessions and Rosenstein chose to short-circuit it. Apparently, the decision to fire an FBI director for only the second time in history was made in less time than it typically takes Justice Department officials to agree where to go for lunch.

To accept this timeline is also to accept that Trump was deeply disturbed by Comey’s treatment of Hillary Clinton during the presidential campaign, despite Trump’s repeated public statements to the contrary. In fact, Politico reported that what actually incensed Trump was Comey’s public statements about the probe of potential ties between Russian hacking and Trump’s campaign team, which prompted the White House to reverse-engineer a process by which Comey could be fired — decision first, justification second.

Let’s be clear: Comey made grave mistakes in his handling of the Clinton email investigation, and I have been as critical of him as anyone. The rules he violated are important to preserving the FBI’s credibility and protecting the rights of individuals under investigation. But one principle must take precedence over every other Justice Department rule or regulation: Prosecutors and agents must be free to make decisions without interference from the White House. Without that, everything else fails.

Trump has now trampled on that independence — with the willing support of the leaders of the department. Where we go from here is uncertain. To start, there can be no remaining question that an independent prosecutor must be appointed to lead the Russia investigation. The attorney general has already recused himself because of his role in the Trump campaign, and the deputy attorney general has now irretrievably stained his own integrity. Both should immediately appear before congressional committees to explain, under oath, their role in Comey’s firing, how the process began and what they discussed with the White House in pursuing it.

But beyond even the Russia investigation lie troubling concerns about the rule of law. The president just fired an official investigating his campaign and associates, crossing a red line once unthinkable in this country. The attorney general quiescently went along. The chairman of the Senate Judiciary Committee said that critics should “suck it up and move on.” The Senate majority leader excused it all in a speech on the Senate floor.

The institutional checks necessary to constrain a president such as Trump are failing before our eyes. If we can no longer count on an independent Justice Department or legitimate oversight from Congress, we are left with one overarching question: Who will stand up to Donald Trump?