Andrew McCabe goes to testify before Congress in 2017.Yuri Gripas / Reuters

When Attorney General Jeff Sessions fired former FBI Deputy Director Andrew McCabe last week, just hours short of McCabe’s retirement, he cited an internal FBI investigation that concluded McCabe “lacked candor” in his conversations with investigators when asked about disclosures to the media during the 2016 election.

But what does that actually mean?

“Lack of candor is untruthfulness or an attempt to dissemble from the point of view of the investigator,” said Dave Gomez, a former FBI agent and a senior fellow at George Washington University’s Center for Cyber and Homeland Security. “The problem comes when, in answering a question, the person under investigation attempts to spin his answer in order to present his actions in the best possible light. This is normal human behavior, but can be interpreted as a lack of candor by the investigator.”

According to former FBI officials, the obligation of bureau employees—agents or otherwise—to have candor in performance of their duties comes from the need for FBI officials to represent the federal government in legal proceedings, act as witnesses in trials, and manage informants. Under the FBI’s standard, candor is not simply telling the truth—it confers an obligation to disclose relevant information even if an investigator has not directly asked about it. The standards are strict—one former FBI official estimated 20 to 30 bureau employees were dismissed annually for matters of candor. In one case described in a 2012 FBI report, an employee was dismissed after she lied to investigators about her husband’s drug use; in another, an employee was fired after they misled investigators about properly disposing of evidence. Another agent lost his job after using his bureau car to transport his daughter to daycare, and then lied about it.

Several former FBI officials pointed to the 1990s, when then-Director Louis Freeh instituted a “bright line” policy with regards to ethics violations, in response to a number of scandals that had embarrassed the bureau, including agents’ mishandling of the Ruby Ridge and Waco incidents. A 2002 Inspector General’s report states that Freeh felt that “the FBI had been too tolerant of certain types of behavior that are fundamentally inconsistent with continued FBI employment,” including “lying under oath, voucher fraud, theft, and material falsification of investigative activity or reporting.” From then on, such violations would be treated as fireable offenses.

“If you have a candor violation, that is treated much more severely than other things that might be more serious, like a DUI,” said Clint Watts, a former FBI agent and a fellow at the Foreign Policy Research Institute. “You have to be able to back up your statements, and if you don’t have good candor, you can’t go jamming people up for lying to federal agents.”

McCabe has denied that he was untruthful to investigators. “The OIG’s focus on me and this report became a part of an unprecedented effort by the administration, driven by the president himself, to remove me from my position, destroy my reputation, and possibly strip me of a pension that I worked 21 years to earn,” McCabe said in a statement released after the firing. “This attack on my credibility is one part of a larger effort not just to slander me personally, but to taint the FBI, law enforcement, and intelligence professionals more generally. It is part of this Administration’s ongoing war on the FBI and the efforts of the Special Counsel investigation, which continue to this day.” Special Counsel Robert Mueller is currently investigating whether anyone associated with the Trump campaign had links to or coordinated with Russian efforts to interfere with the 2016 election, and whether the president sought to obstruct that investigation.

Former FBI and Justice Department officials I spoke to stressed the professionalism of the officials in charge of the Office of the Inspector General and the Office of Professional Responsibility, whose recommendations Sessions said he was following when he fired McCabe. But these former officials, some of whom did not want to be quoted so as not to insert themselves into the controversy, also said they believed the timing of McCabe’s dismissal was suspicious. Candor cases can drag on for months, they said, in part because they can turn on a difference in perception—whether an employee understood the question, or answered to the best of their knowledge, or simply failed to recall something—and often when someone is close to retirement, that person will simply be allowed to retire.

“It’s so weird to rush this right before his retirement, because we don’t really know what the resolution was of the report,” said Watts. “If they didn’t close the entire OPR report, then why are they rushing to fire someone who was caught up in it? It’s so odd that it was so hurried, and it can’t be for anything other than political reasons.”

Even if McCabe’s dismissal turns out to be fully justified on the merits, President Trump’s public attacks on McCabe, the pressure Trump placed on Sessions to fire him, and the timing and circumstances of McCabe’s dismissal ultimately send the message that FBI officials can be fired for doing their jobs, if that conflicts with the president’s interests. “In the end, such conduct necessarily taints the merits of the action against McCabe,” wrote Quinta Jurecic and Benjamin Wittes at Lawfare. “Even if the Justice Department’s process proves pure as the driven snow and the case against McCabe proves compelling, who is going to believe—in the face of overt presidential demands for a corrupt Justice Department—that a Justice Department that gives the president what he wants is anything less than the lackey he asks for? “

The key element of candor cases is that the standard is higher for FBI employees than for the typical government official. The bar for perjury for example, is extremely high and requires prosecutors to prove a defendant’s state of mind. That’s very difficult, which is why few public officials are ever prosecuted for it—even in criminal investigations, it’s typical to charge obstruction rather than perjury. But FBI officials can’t simply avoid lying under oath—even omitting the truth could get them fired.

That higher standard helps shed light on a remark former FBI agent Ali Soufan made to me last week, when he told me that McCabe had been “fired for lack of candor by people who have no candor.” In his confirmation hearing in January 2017, Sessions told then-Minnesota Senator Al Franken that “I didn’t have––did not have communications with the Russians.” After it was revealed that Sessions did in fact meet with Russian Ambassador Sergey Kislyak during the campaign, Sessions’s spokesperson insisted that  he met with Kislyak “in his capacity as a member of the armed services panel rather than in his role as a Trump campaign surrogate.” McCabe oversaw a perjury investigation of Sessions after his testimony, ABC News reported on Wednesday, but such an investigation was unlikely to lead to prosecution. As John Q. Barrett, a law professor at St. Johns University, previously told me, to “prove a perjury case requires not only evidence of knowing falsity but evidence of intent.”

Congressional testimony is often an exercise in avoiding giving damaging answers to direct questions, so perhaps it’s not so surprising that, in the middle of a controversy over whether or not the Russian government sought to aid the campaign of the president who appointed him, Sessions would avoid disclosing his meeting with Kislyak. But the same kind of dissembling in an inspector general’s investigation—I met with him but I didn’t meet with him—might get an FBI agent fired for a lack of candor.

Fortunately for Sessions, as the attorney general, he’s held to a different standard.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.