Sessions’ new sentencing guidelines are advisory—and prosecutors will have the option of seeking approval from their supervisors to pursue lesser charges for low-level crimes. With that in mind, how do you predict federal prosecutors will respond to the new directive?

It is likely that federal prosecutors will follow the directive, although it is important to note that outcomes of directives to prosecutors are far more difficult to track than directives to judges. Prosecutors enjoy wide discretion in the filing of charges—whether to file charges and what charges to file—and in many ways that makes them the most powerful actors in the system. Under mandatory sentencing, the decision to charge can predetermine the sentence in a way that is difficult for judges to circumvent—especially where there are mandatory sentences attached to convictions for certain offenses. In many ways, this directive will place the power to determine the sentence back in the hands of prosecutors.

Holder had directed federal prosecutors to avoid seeking mandatory minimum sentences for certain low-level, nonviolent drug offenders. But Sessions has argued that the Obama administration’s lenient approach toward prosecuting drug cases inspired other crimes, writing in a March memo that “Many violent crimes are driven by drug trafficking and drug trafficking organizations.” How do you foresee his new, more aggressive policy impacting the nation’s violent crime rate? Might it make it easier to bring down large criminal enterprises?

There is no solid evidence that mandatory sentences—or even harsher sentences more generally—have had a substantial effect on crime rates. But it is certainly true that they have had substantial effects on incarceration rates. It is very difficult to determine the drivers of crime rates and the relationship between crime and incarceration is quite complex. It is also generally agreed upon in the field of criminology that supply-side drug enforcement has done little to curb demand for drugs and that the War on Drugs has been a failure. It is certainly true that several drug cartels were damaged by the War on Drugs, but when demand is high, there is always someone else to fill the demand. The takedown of one dealer (small or large) simply makes room for other up-and-coming dealers. This is why many criminologists would argue that the only way to win a war on drugs would be to pursue a demand-side approach. Indeed, this is why in recent years many have argued for public health approaches to drug use and abuse rather than criminal justice approaches.

The Sentencing Project, a nonprofit advocacy center that works to reduce incarceration in the U.S., has called Sessions’ new directive “a devastating revival of the War on Drugs.” How, in your view, might the new policy impact the size of the federal prison population, particularly when it comes to inmates incarcerated due to drug trade?

The majority of offenders in federal prisons have been drug offenders for some time now—a direct consequence of the federal War on Drugs. Without question, if enforced, this directive will become a driver of the federal prison population. Many of the drug offenders incarcerated in federal prisons would be considered relatively low-level players in the drug trade. This is one of the problems with mandatory sentences—they apply equally to the kingpin and the mule. Once an offense is charged (and a conviction secured), mandatory sentences allow for no consideration of individual roles or circumstances—the charge itself dictates the sentence.

In February, Sessions reversed an Obama-era directive to phase out the federal government’s use of private prisons. In what ways could Sessions’ new sentencing policy impact the future of the Federal Bureau of Prisons’ 13 privately run facilities, which currently house approximately 22,000 inmates?

About one-fifth of federal prisoners are incarcerated in private prisons, and as noted, the majority of federal prisoners are drug offenders, so these two directives are related. Holder’s earlier directive intended to divert low-level drug offenders away from prison would have eventually led to reduced federal prison populations. With reductions in federal prison populations, it would follow that there would be less of a need for private prison contracts. These two Sessions reversals can be seen as somewhat inter-related as well. Tougher drug enforcement and the increased application of mandatory sentences will lead to increased prison populations, which may well lead to upticks in the use of incarceration (and of private prison beds). The issue is quite complex, though, because a person can be for heightened drug enforcement and opposed to private prisons, and vice-versa. The point is a more general one—the enforcement of rigid sentencing laws will lead to increases in prison populations—and it was this type of approach that brought us mass incarceration in the first place.