Heather MacDonald in City Journal

In July 2015, President Obama paid a press-saturated visit to a federal penitentiary in Oklahoma. The cell blocks that Obama toured had been evacuated in anticipation of his arrival, but after talking to six carefully prescreened inmates, he drew some conclusions about the path to prison. “These are young people who made mistakes that aren’t that different than the mistakes I made and the mistakes that a lot of you guys made,” the president told the waiting reporters.

The New York Times seconded this observation in its front-page coverage of Obama’s prison excursion. There is but a “fine line between president and prisoner,” the paper noted. Anyone who “smoked marijuana and tried cocaine,” as the president had as a young man, could end up in the El Reno Federal Correctional Institution, according to the Times.

This conceit was preposterous. It takes a lot more than marijuana or cocaine use to end up in federal prison. But the truth didn’t matter. Obama’s prison tour came in the midst of the biggest delegitimation of law enforcement in recent memory. Activists, politicians, and the media have spent the last year broadcasting a daily message that the criminal-justice system is biased against blacks and insanely draconian. The immediate trigger for that movement, known as Black Lives Matter, has been a series of highly publicized deaths of black males at the hands of the police. But the movement also builds on a long-standing discourse from the academic Left about “mass incarceration,” policing, and race.

Now that discourse is going mainstream. As the press never tires of pointing out, some high-profile figures on the right are joining the chorus on the left for deincarceration and decriminalization. Newt Gingrich is pairing with left-wing activist Van Jones, and the Koch brothers have teamed up with the ACLU, for example, to call for lowered prison counts and less law enforcement. Republican leaders on Capitol Hill support reducing or eliminating mandatory sentences for federal drug-trafficking crimes, in the name of racial equity…