“The executive Power shall be vested in a President of the United States of America,” begins Article II of the Constitution. It’s pretty straightforward. The president is the boss of the executive branch. The executive branch is an extension of him. What power it has, he delegates it.

There is no fourth branch of government, so every federal official or employee outside of the court system and Congress works for the president. While civil service laws protect most low- and mid-level employees, the higher-level officials serve mostly at the pleasure of the person sitting in the Oval Office.

As a constitutional matter, then, President Trump has every right to fire an FBI director, a special counsel, his attorney general, or a deputy attorney general. What’s more, he is no more required to give a reason than when he was firing contestants on The Apprentice. None other than James Comey, the FBI director Trump fired, has made that clear. “I have long believed,” Comey wrote, “that the president can fire an FBI director for any reason, or for no reason at all.”

So far, so clear. But can and should are two different things.

Firing Comey was a mistake. Trying to fire special counsel Robert Mueller was a mistake. Threatening to fire Attorney General Jeff Sessions because he recused himself from the Russia investigation was a mistake. These were bad moves by the president, not simply because they have brought him legal and political blowback but because they trammel the independence the president should allow to law enforcement agencies.

For the same reason, Trump was out of line to request loyalty from Comey and to ask Deputy Attorney General Rod Rosenstein if he is on his “side” — as out of line, in fact, as former Attorney General Eric Holder was to describe himself as former President Barack Obama's "wingman." While the FBI and the whole DOJ are extensions of the presidency, they function best when the president gives them independence. He ought to set their priorities (say counterterrorism, cyber crimes, drug crimes, etc.) and make sure the agency isn’t abusing its power.

FBI abuse of power is a real threat. We saw it under J. Edgar Hoover. These people have the spy equipment and the guns. Both Congress and the president need to keep a close eye on them.

And these days, there are bad actors at the FBI. Yet the worst one relevant to today's tumult — former Deputy Director Andrew McCabe, who stayed on the Hillary Clinton investigation despite close monetary and political ties to the Clinton political machine — was ousted by FBI Director Christopher Wray. Oversight from the Office of Inspector General may have contributed to this ouster.

The McCabe incident shows us that the FBI is run by humans, who are fallible. It also shows us that there are many checks in place on the agency by such organizations as the OIG and such political appointees a Wray, without the need for presidential micromanaging.

Independence allows the FBI to do its work without concern of political meddling. In journalism, we grant freedom to columnists; college administrators see the value of academic freedom; and most good employers give their skilled staff a long leash. But in each of these cases, it is proper for the boss to step in occasionally.

With federal law enforcement, ultimate control rests with the president and oversight and funding come from Congress, but the professionals there are to act as independent professionals. They are not supposed to be allies of the president. Equally, they are not supposed to be his antagonists.