Nearly a century ago, one of America’s great jurists, Supreme Court Justice Robert Jackson, defined the role of a prosecutor. Whether a local district attorney or the attorney general of the United States, Jackson made clear that a prosecutor’s duty is not to rack up convictions and impose long sentences. Rather, his or her duty is to ensure “that justice shall be done.”

Given this higher calling, it should not have come as a surprise that Attorney General William Barr chose to intervene in the case of President Trump’s former adviser Roger Stone, who was convicted in November of obstruction of justice, witness tampering and making false statements to Congress.

To be sure, these are serious charges. But when prosecutors at the Justice Department recommended a sentence Monday of seven to nine years in prison for Stone – a 67-year-old first-time offender – it wasn’t just President Trump who was shocked and upset.

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To put it in context, the recommended sentence is more than what an ordinary defendant would serve for basic bank robbery, extortion, or drug dealing.

Stone’s prosecutors used a quirk in the federal sentencing guidelines to justify this outlandish recommendation for such a long prison sentence. They argued that Stone, -- a notorious braggart and attention-seeker -- tried to intimidate a cooperating witness by threatening to kidnap his dog and hoping the witness would die.

However, the cooperating witnesses testified that this was the way he and Stone regularly talked to one another and that he never felt intimidated. Nevertheless, the Justice Department prosecutors used the witness intimidation provision – designed to get at gangs and mob bosses – to pile on Stone, even though no witness was ever actually intimidated by Stone’s antics. When this became public, the attorney general acted. And he should have.

The law requires that a prison sentence should be used to reflect the seriousness of the crime, deter others from the same behavior, and protect the public. But it also makes clear that the time one is sent to prison should be no longer than necessary to accomplish these goals.

Does anyone think that lying to investigators and obstructing an investigation justifies a prison sentence of seven to nine years? Would such a sentence make us safer? Would it serve a greater deterrent than say one to two years? As the judge I clerked for told me when I was fresh out of law school “people forget how long two years in prison really is.” Indeed, we have forgotten.

Given the duty of a prosecutor to do justice, Attorney General Barr had no choice but to act. Certainly, every lawyer in the chain of command had an obligation to ensure that the sentencing recommendation for Stone was fair, transparent and reflective of the actual crimes he was convicted of committing. Unfortunately, the prosecutors failed in their duty. But Barr did not.

Some argue that this is a case of politics eclipsing justice, and indeed, that may be true – but not on the part of President Trump or Barr.

What explanation is there other than politics for prosecutors to recommend such a ridiculously severe sentence for a first-time, non-violent offender other than the fact that the case is connected to President Trump?

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No, the intervention by the attorney general was not the offensive political act. It was an act to fulfill his duty. The political act was the sentencing recommendation by the prosecutors in the Stone case.

Commentators rightly note that it is rare – but not unheard of – for senior law enforcement officials to get involved in sentencing recommendations. While I was a federal prosecutor, I had several cases in which the attorney general and other high-level executives weighed in and exerted influence on my case.

I did not always agree when this happened, but I certainly respected the process. Resigning over such disagreements would have been injecting politics where substance was at issue.

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What Barr sought to do is what many advocates for sentencing reform have been advocating –injection of more reasonableness in the sentencing recommendations of federal prosecutors. Sadly, this does not happen in enough cases.

Every day in courts across the country, Americans face overreaching prosecutors who manipulate the sentencing guidelines to justify draconian sentences. This needs to end. But until it does, our nation will continue to have the highest incarceration rate in the world. If it takes a high-profile case and an attorney general willing to reevaluate, then so be it.