President Richard Nixon says at a news conference on March 15, 1973, that he will not allow his legal counsel to testify on Capitol Hill in the Watergate investigation. (Charles Tasnadi/AP)

Richard Nixon is back — now more than ever! Admittedly, he never quite went away, thanks in part to President Trump, who has argued that an FBI counterintelligence investigation into his associates should be re-branded “SPYGATE,” and constitutes a scandal “bigger than Watergate.” (It does, at least, come in all caps.)

But let’s review. Last spring, when Trump fired FBI Director James B. Comey, we had a chance to review such enduring Nixon tropes as the untimely exit of special prosecutor Archibald Cox and the famous search for a “smoking gun.” This week, the New York Times published a January 2018 letter that Trump’s legal team sent to special counsel Robert S. Mueller III, arguing that — well, many believe we can summarize the argument using Nixon’s infamous comment to interviewer David Frost in the spring of 1977: “When the president does it, that means it is not illegal.”

Nixon’s quote came so quickly to mind for so many because the lawyers’ letter took an expansive position on executive power:

No FBI investigation was or even could have been obstructed. It remains our position that the President’s actions here, by virtue of his position as the chief law enforcement officer, could neither constitutionally nor legally constitute obstruction because that would amount to him obstructing himself. … A President can also order the termination of an investigation by the Justice Department or FBI at any time and for any reason.

As if these claims weren’t enough, presidential adviser Rudolph W. Giuliani added that Trump — unless first impeached and removed from office — could not be criminally indicted, even if he hadn’t just fired Comey but had killed him. The president himself declared, “I have the absolute right to pardon myself.” (That wasn’t an entirely new claim; in July 2017, he said, “All agree the U.S. President has the complete power to pardon.” Not all agree, as I wrote here then.)

The Trump team is arguing for a very aggressive version of the “unitary executive”: the theory that the president controls all aspects of the executive branch, which, therefore, has no power except as he instructs. Under this reading of the Constitution, the president is prosecutor in chief; therefore, he controls what is prosecuted — and what is not. Trump’s claim in December to “an absolute right to do what I want to with the Justice Department” is of a piece with this logic.

This is a Nixonian argument. But it’s not one of the “when the president does it” variety.

That’s because that quote, in the original interview, was aimed at national security concerns. Frost had asked about a White House plan to organize law enforcement and intelligence entities to wiretap, burglarize and infiltrate domestic groups that Nixon felt were dangerous to the country, most of which fervently opposed the U.S. war in Vietnam.

Frost: “Would you say that there are certain situations … where the president can decide that it’s in the best interests of the nation and do something illegal?”

Nixon: “Well, when the president does it, that means it is not illegal.”

Frost: “By definition.”

Nixon: “Exactly, exactly. If the president … approves something because of the national security, or in this case because of a threat to internal peace and order of significant magnitude, then the president’s decision … enables those who carry it out, to carry it out without violating a law. Otherwise, they’re in an impossible situation.”

He went on to argue that “in wartime, a president does have certain extraordinary powers” to override the law.

This is the same argument made by the George W. Bush administration after the 9/11 attacks regarding surveillance, detention and more. Indeed, when it came to statutory prohibitions of torture, the administration argued in 2003 that “to respect the President’s inherent constitutional authority to manage a military campaign, [laws banning torture] as well as any other potentially applicable statute must be construed as inapplicable to interrogations undertaken pursuant to his Commander-in-Chief authority.”

The Trump administration may yet get to that argument — note the opinion issued Friday by the Justice Department’s Office of Legal Counsel regarding April’s controversial airstrikes on Syria. There, the OLC argued that the president “had reasonably determined that the use of force would be in the national interest and that the anticipated hostilities would not rise to the level of a war in the constitutional sense.” In this telling, both the national interest and the definition of war are for the president alone to determine.

But the closer parallel at present is not Frost and Nixon (and definitely not “Frost/Nixon“), but United States v. Nixon. We rightly remember that 1974 case over the fate of the White House tapes as a landmark in executive privilege, as I explained here last year. But a key subplot was whether Nixon had the power to micromanage the prosecutorial process. Leon Jaworski, in the Mueller role, said the president’s taped conversations were key evidence needed to ensure a fair trial for the Nixon aides then being prosecuted. Nixon argued — like Trump —  that prosecution was an executive branch decision and that “the courts are … powerless to determine what material within the executive branch must be used in the case.” Only the president, Nixon said, could make that determination, and he happened to think the tapes were not required evidence.

But Jaworski got the tapes. The court ruled unanimously against Nixon, holding that the regulations that had been issued to protect the special counsel’s autonomy were valid and overrode the president’s claims: “While the regulation remains in effect, the Executive Branch is bound by it.” And in a later case, the court upheld the constitutionality of the Independent Counsel Act and the odd hybrid office of “independent counsel,” buffered from presidential control, that it created.

That case prompted one of Supreme Court Justice Antonin Scalia’s most famous dissents, on the grounds that Article II of the Constitution did not give the president “some of the executive power, but all of the executive power.” But Scalia was the lone dissenter.

The argument is not really about whether presidents control the executive power — but rather about who defines the executive power. And here, as James Madison noted, the answer cannot simply be the president. “The several departments being perfectly co-ordinate by the terms of their common commission,” he wrote, “none of them, it is evident, can pretend to an exclusive or superior right of settling the boundaries between their respective powers.”

In short, the most extreme “unitarian” arguments run up against a key founding principle: The Constitution is avowedly trinitarian.