On Monday, federal prosecutors recommended that Republican operative and Trump associate Roger Stone be sentenced to seven to nine years in prison for crimes including witness tampering and making false statements. In the middle of the night, the president lashed out, tweeting that the sentencing request was “horrible,” “very unfair” and a “miscarriage of justice.” The following day, all four prosecutors withdrew from the Stone case, with one, Jonathan Kravis, immediately resigning from the Department of Justice.

Later that day, the interim U.S. attorney for D.C., Timothy Shea — a former adviser to Attorney General William P. Barr — filed an updated memo saying that the original sentencing request “did not accurately reflect the Department of Justice’s position on what would be a reasonable sentence” and the sentence originally requested “would not be appropriate or serve the interests of justice in this case.”

This series of events sent shock waves through the network of former Justice Department prosecutors and officials. Why? Because it signals a new and dangerous chapter in the politicization of the department by Donald Trump and William Barr.

Stone’s conviction in November was secured by a team of career public servants who prosecuted the case ethically, professionally and successfully, securing convictions on all seven counts. As in nearly every federal case, once a defendant is found guilty, the U.S. Probation and Pretrial Services Office, an arm of the court, prepares a report calculating the applicable sentencing range. In Stone’s case, that sentencing range was determined to be seven to nine years in prison. Such guidelines are used in every federal case to come up with a fair and appropriate sentencing range.

Not surprisingly, the prosecutors agreed that seven to nine years was indeed appropriate for Stone, given federal guidelines. It is extremely rare for prosecutors to recommend a sentence below the guideline range especially when, as here, there are aggravating factors. Stone attempted to tamper with witnesses while he was being prosecuted and antagonized the judge by violating a gag order.

So, let’s be clear about what this controversy is not about: This isn’t about what Stone’s actual sentence should be or whether the Federal Sentencing Guidelines are inappropriate. Conservatives complaining that Stone’s sentencing recommendation was so harsh it warranted DOJ interference are missing the point. If Trump and his allies want to have a discussion about sentencing reform — for all defendants, not just ones the president wants to protect — we can do that in a separate conversation.

This is about the attorney general and political appointees reversing decisions of career prosecutors without cause. Americans trust prosecutors to make decisions every day in our justice system that are based on facts and law, not politics or cronyism.

But more important, there can be little doubt that this dramatic turnabout in the prosecution’s sentencing recommendation was the product of political meddling. Such meddling has infected the DOJ and is clearly impairing its ability to function. Trump’s tweet Wednesday morning confirms this.

The DOJ has been able to function despite the corruption and chaos of the Trump administration in large part because of the rank and file career prosecutors. These men and women serve under both Democratic and Republican administrations (as we both did as assistant United States attorneys who served regardless of the politics of any particular administration) and are supposed to be insulated from the political whims of presidents or other outside forces. The political appointees — the attorney general and United States attorneys — are supposed to ensure that politics do not influence charging or sentencing decisions.

This is a matter of principle, and it is vitally important to both the Department of Justice and America’s justice system overall. But the system is only as strong as the people who serve it. Instead of standing up to his new boss, Timothy Shea put politics in front of principle. (Adding insult to injury, it seems Shea’s predecessor was prematurely removed from the job by Barrr.)

When both the U.S. Probation Office and the Pretrial Services Office and the prosecutors who know the case best agree that a seven- to nine-year sentence is appropriate, the fact that a presidential tweet can result in a reduced sentence is a sign that the criminal justice system is being corroded from the inside out. It is a move that smacks of cronyism, favoritism and exploitation.

We already witnessed plenty of evidence that this was happening during Robert Mueller’s investigation, especially from the attorney general. Barr’s gross distortion of the Mueller report’s findings led to calls for him to step down. He did not. And now we are facing the same situation all over again.

The DOJ is turning into an organization that unjustly pursues the president’s perceived enemies and unjustly favors his friends, allies and cronies. And it’s happening right in front of our noses. The resignations this week are only the latest alarm bells. But the fire’s been burning for months.