Sen. Mitt Romney, R-Utah, on Saturday denounced President Trump’s commutation of Roger Stone’s prison sentence as “unprecedented, historic corruption.” But as former prosecutors, we believe the Stone prosecution was always a questionable waste of resources, with a shaky factual basis and marked by blatant politicking.

The Stone prosecution is just the latest example of a well-documented phenomena: the way special prosecutors, desperate to justify their commissions, end up charging marginal players with tangential crimes — often related obstruction of the investigation itself.

Stone was a relative bit player in the investigation by Special Counsel Robert Mueller into alleged collusion between Trump’s presidential campaign and Russian agents in 2016. As the world now knows, Mueller concluded there wasn’t any.

But a feature of special prosecutions is that they spawn numerous criminal cases unrelated to the underlying allegation. The most obvious example is Ken Starr’s investigation of President Clinton’s business dealings. That probe uncovered Clinton’s affair with intern Monica Lewinsky and eventually led to Clinton’s impeachment by the House of Representatives, followed by his acquittal in the Senate.

But just about every special prosecutor since the 1980s has generated similar convictions of bit players, often for obstructing the investigation itself.

That’s what happened to Roger Stone. There was never much evidence that Stone — a braggart who reveled in political theater — had any contact with Russian agents or material evidence for Mueller to work with.

But Stone tried to browbeat another marginal witness into not cooperating, and allegedly lied to investigators when asked about his contacts with WikiLeaks. And so Stone was indicted on seven counts of tampering and obstruction.

This is an old story: an underlying investigation that results in no directly relevant criminal charges and spawns a mess of felony charges for obstructing an investigation that went nowhere.

In a normal prosecutor’s office, which has thousands of pressing matters and limited resources, Stone likely would never have been indicted, or would have faced a relatively light charge. Believe it or not, this is a good thing — limited prosecutorial capacity is an important check on prosecutorial overreach and helps to focus resources on truly important matters.

But special prosecutors, with near-limitless budgets and little meaningful oversight, tend to become perpetual motion machines. They generate new criminal charges further and further distant from the original allegation that caused the appointment in the first place.

It is this tendency, among others, that led the late Supreme Court Justice Antonin Scalia, in his dazzling dissent in a case that upheld the special counsel law, to describe them as a wolf that, far from being dressed in sheep’s clothing, “comes as a wolf.”

Special prosecutions are also inevitably politicized. From the day he was arrested — in a showy predawn SWAT raid that news media were tipped off to — Stone’s prosecution became a litmus test for your opinion about Donald Trump.

The forewoman of the jury hearing the Stone case let loose with anti-Trump, anti-Stone sentiments on social media and anointed herself a member of “the resistance.”

Line prosecutors asked for a facially absurd 7 to 9 year sentence for Stone, and then resigned when the Attorney General William Barr tempered the recommendation — something that happens regularly inside the Justice Department in high-profile cases, and that is well within the attorney general’s discretion.

Even the more measured 40-month sentence Stone received was far too long for the relatively picayune factual basis for the prosecution, though many Democrats called it a miscarriage of justice.

As a former judge once told one of us as a newly minted law clerk, people have lost sight of just how long a two-year prison sentence is.

Though Roger Stone and Eric Garner — who died in a police chokehold because he was selling loose cigarettes on a New York City street — have little in common, they are both examples of the dangerous over-criminalization of American life.

The criminal law has become so complex and so extensive that none of us would be unindictable if a prosecutor with endless resources decided to hone in on us. This is a recipe for mass incarceration and politicized justice.

Democrats and Sen. Romney denounced the Stone commutation. But permitting an elderly non-violent offender to avoid incarceration in the middle of a deadly viral pandemic is hardly a miscarriage of justice.

We wish the Justice Department and President Trump had done more to commute sentences during this time, when tens of thousands of state and federal inmates have been infected with COVID and hundreds have died. Prison terms aren’t supposed to be a death sentence, even for your political opponents.

What you think about Roger Stone’s commutation is likely correlated with your feelings about Donald Trump. That is unfortunate. The legal system cannot function if people believe it to be politicized, as record numbers of Americans of all political persuasions now do.

But unfortunately, Stone’s close association with Trump has always clouded a dispassionate analysis of the case against him. Viewed that way, it was always mighty thin.