Meanwhile, Mr. Sessions, who as a senator was one of the most reliable roadblocks to long-overdue federal sentencing reform, is still throwing wrenches into the works as Congress inches toward a bipartisan deal. Mr. Sessions called the Sentencing Reform and Corrections Act, a sweeping bill that would reduce some mandatory-minimum sentences, and that cleared the Senate Judiciary Committee on Thursday, a “grave error.” That earned him a rebuke from the committee’s chairman, Senator Charles Grassley, who pointed out that the attorney general is tasked with enforcing the laws, not writing them. “If General Sessions wanted to be involved in marking up this legislation, maybe he should have quit his job and run for the Republican Senate seat in Alabama,” Mr. Grassley said.

Mr. Grassley is no one’s idea of a justice reformer, but he supports the bill because, he said, it “strikes the right balance of improving public safety and ensuring fairness in the criminal justice system.”

So what has this administration done right? The list is short and uninspiring. In October, Mr. Trump declared the epidemic of opioid abuse a national emergency, which could be a good step toward addressing it — but he’s since done almost nothing to combat a crisis that killed more than 64,000 Americans in 2016.

In his State of the Union address last month, Mr. Trump promised to “embark on reforming our prisons to help former inmates who have served their time get a second chance.” It’s great if he really means that, but it’s hard to square his assurance with his own attorney general’s opposition to a bill that includes recidivism-reduction programs intended to achieve precisely this goal.

Perhaps the most insidious part of the Trump administration’s approach to criminal justice lies in its efforts to link crime to its broader crackdown on immigration. In a speech last month, Mr. Sessions said undocumented immigrants are far more likely than American citizens to commit crimes, a claim he found in a paper by John Lott, the disreputable economist best known for misusing statistics to suit his own ideological ends. In this case, it appears Mr. Lott misread his own data, which came from Arizona and in fact showed the opposite of what he claimed: Undocumented immigrants commit fewer crimes than citizens, as the vast majority of research on the topic has found.

But no matter; Mr. Trump and Mr. Sessions don’t need facts to run their anti-immigrant agenda, which has already resulted in more than double the number of arrests of immigrants with no criminal convictions as in 2016, as the Brennan Center report noted. Soon after taking office, Mr. Trump issued an executive order cutting off federal funding to so-called sanctuary cities, jurisdictions that refuse to cooperate with federal immigration officials. A federal judge blocked the order in November for violating the Constitution.

The rhetoric from the White House and the Justice Department has emboldened some state and local officials to talk tougher, even if just as ignorantly, about crime. The good news is that it’s not working as well anymore. In Virginia’s race for governor last fall, the Republican candidate, Ed Gillespie, attacked his opponent, Ralph Northam, with ads blaming him for violence by the MS-13 gang.

It was a despicable stunt, its fearmongering recalling the racist but effective Willie Horton ad that George H. W. Bush ran on in his successful 1988 presidential campaign. Thankfully, Virginia’s voters overwhelmingly rejected Mr. Gillespie, another sign that criminal justice reform is an issue with strong support across the political spectrum. In the era of Donald Trump, candidates of both parties should be proud to run as reformers — but particularly Democrats, who can cast the issue not only as a central component of a broader progressive agenda, but as yet another example of just how out of touch with the country Mr. Trump and his administration are.