Will we ever learn the dangers of unleashing a special counsel? By “we” I mean the country, the federal government, the Justice Department, and the person chosen to do the job of investigating and deciding if a crime has been committed.

In the beginning, the naming of a special counsel comes as a relief. There’s been a sensational case of possible wrongdoing by a government official, and the special counsel will determine, in secret, what should be done about it. The rest of us can relax and go about our daily lives.

But one thing is overlooked: the great temptations a special counsel faces. In this case, Robert Mueller was supposedly accountable to Deputy Attorney General Rod Rosenstein. In effect, he was on his own.

He was free to hire whomever he wanted as investigators. He could continue the investigation for as long as he wished. He could extend his reach far outside the narrow confines of his original assignment to find if the Trump campaign had conspired with the Russians to tilt the 2016 election in his favor. And Mueller took advantage of all those opportunities.

[ Opinion: Robert Mueller should testify before Congress]

But he neglected the implicit requirement of his job to bring the matter to a close. He needed to tie up any loose strings, make final decisions on the various aspects of the case, and put the whole matter behind him and the country. That’s what he was expected to do.

Mueller did the opposite. In his report, he said there was no evidence of a conspiracy with the Russians. But on the secondary issue of obstruction of justice, whether President Trump had criminally attempted to impede the investigation, Mueller punted. He left the matter open while noting that the official guidance of the Justice Department holds that a sitting president cannot be indicted while he’s in office.

That wasn’t all. He stuffed the report with page after page of examples of possible obstruction, including the famous order to White House counsel Don McGahn to arrange to get Mueller fired, which the president denies happened. Former federal prosecutor Andrew McCarthy, writing in National Review, called this tactic “smear-but-don’t-charge.” If nothing else, it seemed aimed at keeping the issue of possible Trump wrongdoing alive.

Indeed, it has had exactly that effect. The entire anti-Trump establishment — Democrats, the Left, the media — jumped on it. They quickly moved the goal posts. Collusion was forgotten. Obstruction became paramount.

[ Related: Barr testimony reveals split with Mueller on obstruction]

Attorney General William Barr and Rosenstein considered the examples and decided none amounted to criminal obstruction. But the Democratic House dismissed that view and mass produced subpoenas. And when Trump asserted executive privilege, denying the House Judiciary Committee’s request for an unredacted copy of Mueller's report and the underlying evidence, the committee recommended Barr be held in contempt.

Adding a dramatic touch, Chairman Jerry Nadler, D-N.Y., announced, “We are now in a constitutional crisis.” He exaggerated, but there is a serious dispute over the conflicting constitutional powers of the White House and Congress. Resolving it in court could take months, even years.

Who’s to blame for this mess? Mueller. All he had to do was what a prosecutor does: Unless he’s persuaded an indictment is justified, he’s obligated to drop the case. But temptation got the better of Mueller.

What was the temptation? Special counsels are known to many as special prosecutors and often act accordingly. They fear completing their work without leaving convictions behind. In special counsel Patrick Fitzgerald’s case, when he didn’t have evidence to indict Vice President Dick Cheney, he manufactured a specious perjury charge against Cheney’s chief of staff, Scooter Libby.

[ Opinion: The false dichotomy of the Mueller report]

Mueller’s substitute for a conviction or indictment was the list of examples of possible evidence of obstruction of justice. It took the place of counts in an indictment.

There’s been speculation the examples were the work of Mueller’s investigators. McCarthy wonders if Mueller’s “notoriously aggressive staffers, recruited from the Obama Justice Department and private practice stints representing the Clintons” were “running this show.”

It really doesn’t matter. Mueller was in charge, and the report has his name on it. All his sins were ones he was set up for by being a special counsel in the first place. It’s time never again to appoint a special counsel and then subject him to powerful temptations to which he is likely to succumb.

Fred Barnes, a Washington Examiner senior columnist, was a founder and executive editor of the Weekly Standard.