The preamble to the United States Constitution makes clear what our system of government is supposed to do with its power and authority. In fact, the 16th and 17th words in the document say that the American system should exist in order to "establish justice."

The constitutional mandate is under attack in ways without modern precedent.

The entire team prosecuting Roger Stone abruptly resigned from the criminal case on Tuesday after the Justice Department said it planned to reduce the recommended sentence for Stone, a longtime Donald Trump associate.

There was a frequently used phrase at the start of the Trump presidency: "This is not normal." It was intended to help capture the extraordinary circumstances Americans were witnessing, as the nation's first amateur president, indifferent to constraints, pushed legal and political boundaries in ways our system of government was unprepared for.

In time, however, the phrase faded -- not because Trump grew more responsible, but because the political world started to grow accustomed to the Republican's radical tactics.

With this in mind, it seems like an opportunity to revisit the phrase. Let no one say yesterday's events were normal.

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To be sure, the actions surrounding the case against Roger Stone, a longtime Republican operative and Trump ally, seemed rather routine. Stone was charged with multiple felonies, given a fair trial, convicted by a jury, and was prepared for sentencing. Federal prosecutors recommended a sentence that was in line with existing sentencing guidelines and made their case to a judge, in writing, defending their rationale. All of this unfolded exactly as it was supposed to.

But after the president condemned the prosecutors' filing on Twitter, Attorney General Bill Barr's Justice Department intervened, declaring that it was withdrawing the recommended sentence. As the afternoon progressed, four prosecutors -- one at a time -- announced their resignations.

The case is being handled by the U.S. Attorney's office in Washington, D.C., where Jessie Liu, who was leading the office, was replaced two weeks ago by Timothy Shea -- Barr's longtime aide.

This is what it looks like when a nation's system of justice begins to unravel under the weight of partisan political intervention. A Justice Department that overrides its own prosecutors to do favors for the president's pals is a department that should expect to be seen as corrupt.

Mary McCord, a former prosecutor and acting assistant attorney general for the department's national security division, told the Washington Post, "There is no way you can come away from this with anything other than an impression that Justice is taking its orders from the president and pandering to the president. This is causing lasting and long-term damage to the department's reputation and credibility."

The same report quoted Rep. Bill Pascrell Jr. (D-N.J.) saying, "We are seeing a full-frontal assault on the rule of law in America. Direct political interference in our justice system is a hallmark of a banana republic. Despite whatever Trump, William Barr, and their helpers think, the United States is a nation of laws and not an authoritarian's paradise."

The Democratic congressman suggested the intervention in the Stone case amounted to "obstruction of justice."

On Twitter, David Laufman, the former counterintelligence chief at the Justice Department, called yesterday's developments "shocking," adding, "We are now truly at a break-glass-in-case-of-fire moment" for the DOJ.

Michael Bromwich, the former Justice Department inspector general, wrote in a message to career employees at the DOJ, "This is not what you signed up for. The four prosecutors who bailed on the Stone case have shown the way. Report all instances of improper political influence and other misdeeds to the DOJ IG, who is required to protect your identity."

Some Senate Democrats pushed for the Senate Judiciary Committee to investigate what transpired, but with the committee led by Chairman Lindsey Graham (R-S.C.), few seriously expect the Republican-led panel to take the rule-of-law emergency seriously. Senate Democratic leaders have also formally requested a probe from the Justice Department's inspector general's office, but it's not yet clear what, if anything, will come as a result of the appeal.

The prospects for proper oversight are far better in the Democratic-led House. Watch this space.