By Lily Rothman
January 26, 2018

After months of speculation about whether or not President Donald Trump might be tempted to fire Special Counsel Robert Mueller, who is leading the investigation into Russian meddling in the 2016 election, the New York Times reports that Trump actually did order Mueller fired last June — only to back down after top White House lawyer Donald McGahn threatened to quit.

Trump has dismissed the report as “fake news.” His critics have seized on it, with Virginia Democratic Sen. Mark Warner saying that such an action would be crossing a “red line.” And while that may be the case as far as modern political norms are concerned, Trump technically does have the power to have a special counsel like Mueller fired — and the reason goes back to the Constitution.

Katy Harriger, a professor at Wake Forest University and author of The Special Prosecutor in American Politics, says that’s because of the complicated history of the job Mueller holds. The job has gone through many permutations over the many years since it was first used in response to the Whiskey Ring scandal of the 1870s, but it’s important to note that the theoretical underpinnings of the President’s power over such a position go back to the beginning. “In Article II [of the Constitution] it does say that he has to take care that the laws are faithfully executed – that’s the source of his enforcement power,” Harriger says. “The courts said a long time ago that officers who are executing that power on behalf of the president have to be removable by him.”

The way the rules are currently written, the special counsel reports directly to the person who appointed him, Harriger says — in Mueller’s case, that’s Deputy Attorney General Rod Rosenstein. But again, Rosenstein’s power can, ultimately, be traced back up to the President. As a result, just as was the case with Richard Nixon’s infamous Saturday Night Massacre, a historical episode that has been oft-invoked in recent months, Trump could ask the people below him to fire the person he wants fired, and if the person in the middle objects, he or she can resign or be fired until someone in the chain of command obeys. (Plus, Harriger notes, that procedure is a matter of convention rather than constitutional requirement, so the President could choose to defy convention and do the firing himself, though doing so might provoke litigation.)

Still, even if someone else pulls the trigger, it’s the President’s authority behind that decision.

For a while, however, things were different.

In the wake of Watergate and 1973’s Saturday Night Massacre, Congress took steps to stop future Presidents from going after people who were appointed to investigate them. In “direct response” to the Saturday Night Massacre, Harriger says, the Ethics in Government Act changed the way that system worked. (Not that Watergate was the first time someone in Mueller’s place has been driven out. But, when a special investigator was fired in the other noteworthy episode, amid a tax scandal in the Truman administration, outrage was muted because Truman was not personally implicated in any wrongdoing, and the prosecutor was widely seen as having overstepped the bounds of his job.)

The law gave a panel of judges the power to pick a special prosecutor at the request of the Attorney General, and set out exactly how he or she could be fired: The special prosecutor could be “removed from office, other than by impeachment and conviction, only by the personal action of the Attorney General and only for extraordinary impropriety, physical disability, mental incapacity, or any other condition that substantially impairs the performance of such special prosecutor’s duties.” In addition, there were specific procedures set out for reports on and review of such a removal.

But when the law expired in the 1990s, it was not renewed.

Harriger traces that decision to a late-Clinton-era perception that the mechanism for investigating the President had been used unwisely. In its place, internal Justice Department regulations were set up to pick independent counsels.

In one sense, Harriger says, her research has shown that the new system insulates the investigator from party politics — it is harder to dismiss a finding of wrongdoing if the investigation is being overseen by someone working for the same Executive Branch that is being investigated. On the other hand, it also means the authority to dismiss such investigators for a wider variety of reasons returned more fully to the Justice Department, and hence, through the chain of command, to the President.

“When the statute existed it was a limitation on the president’s power to control that person and the Supreme Court upheld that as within Congress’ authority, but in this case we don’t have anything Congress has written. Now it’s just internal regulations,” Harriger says. “If the statute had been around now, it would be different situation today.”

Write to Lily Rothman at lily.rothman@time.com.

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