Because the appeals process stays within the executive branch, his chances for success would appear to be nil. “There’s no one in the executive branch who is a higher authority than the president,” Aftergood said. “It’s not clear to whom the decision would be appealed.”

Brennan’s other option—one that he says he is considering—is to take the president to court and seek an injunction while he presses his case on the grounds that Trump infringed on his First Amendment right to free speech. “I am going to do whatever I can personally to try to prevent these abuses in the future,” Brennan said Sunday on Meet the Press, “and if it means going to court, I will, I will do that.” Nick Shapiro, a spokesman for the former CIA director, told me he had not made a decision as to whether to sue.

Hayden, who served as the director of the National-Security Agency and then the CIA in the George W. Bush administration, said he and Brennan have heard from lawyers who offered to bring a case challenging the president’s power. (Hayden has not yet had his clearance revoked.)

“Was this so abnormal, so out of the normal turn of events, so absent of process, that it was an illicit use of what was, and is, an inarguable presidential authority?” Hayden told me, summarizing what a lawsuit would seek to answer.

An admiral speaks out

Trump and his lawyer, former New York City Mayor Rudy Giuliani, have tried to goad Brennan into filing a lawsuit, and the president has acknowledged that he was elevating Brennan in part because he relished a fight with him.

But some national-security lawyers want Brennan to sue too, even if his chances of victory are slim. “I think the case law is really clear from a practical, realistic standpoint that Brennan would not be able to make any substantive progress in a lawsuit,” said Mark Zaid, a national-security lawyer who has experience representing whistle-blowers and federal officials who have had their clearances suspended or revoked. He cited a 1988 Supreme Court case in which the justices confirmed that the executive branch has broad authority to deny someone a security clearance on national-security grounds.

But, as Smith wrote last week in The New York Times, that case was decided on a procedural basis, not on the First Amendment grounds on which Brennan would presumably base a lawsuit. And Zaid said he would eagerly represent Brennan in such a case, no matter how much of a long shot it was. “When it comes to the national-security arena, many times where we bring a case, we’re not bringing a case with an expectation of a win,” he told me. “In fact, we expect to lose, quite frankly, a majority of the time.”

“But,” Zaid continued, “as long as we’re not bringing a frivolous case, we can bring that case with the hope that we can raise the issue that is at play.”