BU Today: Trump obviously feels unfettered from the traditional restraints on the office of the presidency. Will his acquittal have lasting effects on future presidents?

Whalen: Absolutely. The constitutional principle of congressional oversight is now shredded. A president, even during an impeachment process, can refuse to produce documents and witnesses based on this expansive view of executive privilege. The whole idea of balance of power that the Founders set up, checks and balances, is completely gone.

Moving forward to, say, building the so-called wall on the Mexican border, Trump can now say, “I don’t have to produce documents or administration members to testify before Congress, because I deem it unnecessary or because I can do whatever the heck I want.”

What happens when you have a different personality in a future president?

History has demonstrated, whether you’re a Democrat or a Republican, if the executive branch is granted greater power, you are not going to give it back. Think back to the last declared war in American history, World War II. Under our constitution, only Congress has the right to declare war. Well, ever since then, we’ve had quite a few wars, but the president has taken the war-making power from Congress. Once the horse is out of the barn, you can’t get it back in.

That’s why I’m so concerned about what just happened during the impeachment process. The only power [Congress] really has left is controlling the purse strings, but we’ve already seen that being weakened during the Trump presidency. When he’s trying to build the wall, he has, without consulting Congress, taken funds from other parts of the budget.

What do you think of the defense team’s arguments?

Dershowitz’s argument made me fall to the floor. It is an authoritarian argument, that every four years we elect the equivalent to a Roman emperor, and no matter what he does, he is above the law as long as he feels that it’s in the national interest. I’m sure Jesse James thought he was doing a good thing by robbing people.

Is this all Trump’s fault?

It’s not. It’s a Democrat and Republican trend. George W. Bush and Barack Obama weren’t shy in exerting executive power, even expanding it—the whole idea of signing statements [written presidential declarations that a president will interpret a just-signed bill in a certain way], where you basically interpret the law not as Congress puts it down, but as the executive branch interprets it. Trump represents a culmination of the imperial presidency. He just sped up the process a bit. Probably to his own surprise, his own party has been so accommodating of him.

You have no sympathy with scholars who say we have too many handcuffs on the president, that we need—

“The unitary presidency.” No, and the irony is that what’s behind the unitary presidency is national security. Truman created the national security state in the late 1940s while we were fighting an existential threat [the Soviet Union]. Here is Trump undermining national security by throwing an ally under the bus, to whom? Russia.

If acquittal will give too much power to the executive branch, what’s the solution? Do you see one?

I don’t. I’m pretty pessimistic. I’ve been thinking of Octavian Caesar of late. He shut down the Roman Republic, but he did it in an ingenious way. He kept all of the institutions in place, like the Senate, but he loaded it with his loyalists, and basically, he became the sole power. He destroyed the Republic, but presented himself as the savior of the Republic. He did it from within. This was after the Roman Civil War, a turbulent time, just as Trump has taken advantage of a very turbulent time in American history.

And that’s how authoritarians rise to power. I think, unfortunately, what we’re seeing here is a slide toward authoritarianism. I hope I’m wrong.