Today, the president of the United States, Donald Trump, has expressed admiration for the strength of Vladimir Putin, the Chinese leaders behind the Tiananmen Square crackdown, and the strongman who runs the Philippines. After Trump’s rise, but before he was elected, I again urged Obama, and House and Senate Republicans who faced the possibility of a Hillary Clinton presidency, to “Tyrant Proof the White House––Before It’s Too Late.” Elected officials failed to take action.

So I am predictably alarmed that Trump will now be naming his own pick to run the FBI. But that’s no surprise, and presumably unpersuasive if you weren’t with me already.That’s why I want to introduce you to Benjamin Wittes, who almost always disagrees with me and other civil libertarians, downplaying the possibility of government abuses.

Over all the years that I’ve been sounding alarms about drone strikes and NSA surveillance, Wittes has retorted that civil libertarians like me are being unduly alarmist. During a debate on lethal drone strikes at the University of Richmond, when I urged a moratorium, Wittes took the lectern and mounted an emphatic defense of drones. When Edward Snowden revealed mass surveillance on U.S. citizens, sparking alarmed calls from civil libertarians like me for sweeping NSA reforms, Wittes insisted that the professionalism of NSA staffers and existing checks within the executive and legislative branches were sufficient to protect Americans.

This man is as informed as anyone about the workings of the national-security bureaucracy and federal law enforcement. And his predisposition is nearly always to trust it.

So I’d never choose Wittes to serve as my canary in a coal mine. I’d be afraid that he would somehow manage to keep chirping merrily even as all the miners had suffocated. But for those inclined to use heuristics to determine when to worry, Wittes is very useful. If even he is alarmed at the potential for abuse, everyone should be alarmed.

Let us now delve into his thinking on Comey.

Last spring, when I urged Obama to tyrant-proof the White House, to the extent possible, before his successor was sworn in, Wittes didn’t abandon his bygone positions. He maintained that concerns about drone strikes or mass surveillance were silly. But he did add, “There are, to put it mildly, more proximate concerns.” It was like the scene in Butch Cassidy and the Sundance Kid where bounty hunters chase the outlaws to the edge of a cliff above a river. Sundance doesn’t want to jump. He can’t swim. “Are you crazy?” Butch retorts. “The fall will probably kill you.”

So what finally worried one of Washington, D.C.’s most consistent critics of civil libertarians?

Here’s what:

Let me be blunt: The soft spot is not NSA and it's not the drone program. The soft spot, the least tyrant-proof part of the government, is the U.S. Department of Justice and the larger law enforcement and regulatory apparatus of the United States government. The first reason you should fear a Donald Trump presidency is what he would do to the ordinary enforcement functions of the federal government, not the most extraordinary ones… A prosecutor—and by extention, a tyrant president who directs that prosecutor—can harass or target almost anyone, and he can often do so without violating any law. He doesn't actually need to indict the person, though that can be fun. He needs only open an investigation; that alone can be ruinous. The standards for doing so, criminal predication, are not high. And the fabric of American federal law—criminal and civil law alike—is so vast that a huge number of people and institutions of consequence are ripe for some sort of meddling from authorities. A template here is how former Virginia attorney general Ken Cuccinelli was able to harass climate scientists he didn't like. This stuff is not hard to do, and you don't even need to win to succeed. The Justice Department has some institutional defenses against this sort of thing, but they are far weaker than the intelligence community's institutional defenses against abuses. They mostly do not reside in statute or in the sort of complex oversight structures that Granick complains in the case of NSA are not restrictive enough. They reside in the Levi Guidelines, in certain normative rules about contacts between the Justice Department and the White House, in norms that have developed over the years in the FBI. And they reside in the hearts of a lot of replaceable people. Ultimately, they reside in an institutional culture at the Justice Department, and that is precisely the sort of thing a tyrant leader can change.

Wittes went on to sketch what a would-be tyrant would need to do to effect that sort of change. “He would need to appoint and get confirmed by the Senate the right attorney general,” he wrote. “That's very doable.” Indeed, we now know his name: Jeff Sessions.