You might have noticed that there is a concerted effort by many conservative groups in recent years to reduce the prison population. Groups like the American Conservative Union and Right on Crime have come out in favor of legislation that reduces the sentences imposed on criminals in federal prison.

Recently, Attorney General Jeff Sessions raised the hackles of some of these groups by issuing a directive that “could potentially ramp up criminal charges in cases involving nonviolent drug crimes,” according to CNN.

Here is Christina Delgado of the nominally conservative R Street Institute:

Attorney General Jeff Sessions’ memorandum instructing federal prosecutors to “charge and pursue the most serious, readily provable offense” against defendants signals a desire to return to a tough-on-crime stance. From the perspective of criminal justice reform, the most daunting aspect of these developments is a likely resurgent dependence on mandatory minimums…. [Recently], experts have gathered evidence against mandatory minimums, finding that heavy use of these sentencing laws failed to reduce drug use or recidivism. Mandatory minimum sentences are fixed prison terms applied to specific crimes, which can range from five years to life imprisonment. They strip judges of the ability to use their own professional discretion to determine sentencing based on the facts at hand. The aim of mandatory minimums during the height of the 1980s crack epidemic was, of course, to target drug kingpins and cartel leaders, in order to improve public safety. Prison populations surged, but it was primarily due to an increase of low-level offenders. With prisons now bursting at the seams and calls for the construction of newer prisons to house an ever-growing population of prisoners, taxpayers have had to shoulder the costs.

Is it fair to judge mandatory minimum sentences by whether they reduce recidivism? Rehabilitation programs aimed at reducing recidivism have had a spotty record at best. Indeed, it was the emphasis on rehabilitation or imprisonment beginning in the late 1950s that was in part to blame for the crime wave of subsequent decades. One of the main purposes of mandatory minimums was to keep criminals in prison; the purpose was never rehabilitation.

Indeed, Delgado appears to forget another purpose of mandatory minimums when she complains that they “strip judges of the ability to use their own professional discretion to determine sentencing based on the facts at hand.” That many liberal judges use their professional discretion to sentence not based on the facts of the case but on their own belief that we shouldn’t treat criminals “harshly” is what led to mandatory minimums. Mandatory minimums ensured that liberal judges would be forced to lock them up.

Finally, mandatory minimums worked. As the number of criminals in prison rose, the crime rate dropped.

Much of this push derives from some conservatives’ desire to end the “war on drugs.” According to this line of thinking, the drug war has caused, as Michelle Malkin recently put it, “Overcrowded jails teeming with nonviolent drug offenders.”

The reality is dramatically different. As the indispensable Heather Mac Donald of the Manhattan Institute found, “47 percent of incarcerated Americans are in prison for violent crimes, compared with only 20 percent for drug-related crimes.” Nor are prisons bursting at the seams with recreational pot smokers. “Less than 1 percent of sentenced drug offenders in federal court in 2014 were convicted for simple drug possession, according to the U.S. Sentencing Commission, and most of those convictions were plea-bargained down from trafficking charges,” according to Mac Donald. Most are in prison for drug trafficking.

In 2014, California voters approved Proposition 47 which reduced the number of criminals in that state’s prison and jails. Surprise, surprise – crime rates increased. Let’s hope the political right will fail at achieving the same at the federal level.