In a memorandum providing new federal enforcement guidelines for anti-drug laws, Attorney General Jeff Sessions imprudently required government prosecutors to take a freshly hard-line approach.

Although respect for the rule of law is essential, and a firm federal hand on nationwide criminal justice matters is important, the memo cuts too hard against the grain of federalism and runs counter to hard policy lessons learned over the long course of America’s war on drugs.

Sessions’ wording shows some potential moderation or ambivalence. Federal prosecutors are ordered to “charge and pursue the most serious, readily provable offenses,” which would generally imply a focus on the biggest shipments and most flagrant abuses of the hardest of drugs.

On the other hand, the memo instructs prosecutors to seek convictions that “carry the most substantial guidelines sentence, including mandatory minimum sentences.” It is hard not to view this language as signaling an end to the hands-off approach former Attorney General Eric Holder took with regard to the decriminalization of marijuana at the state level.

Although Holder’s policy may have been presented or carried out more cavalierly than some Americans were comfortable with, Sessions’ change of course flies in the face of important realities on the ground that now enjoy political legitimacy.

Legalized pot tends to result in larger scale but smaller infractions of federal anti-drug law, with organized crime moving into different (and harder) drugs to make significant profits. Replacing prosecutorial discretion with a policy of seeking punishment for every violation to the maximum extent of federal law suggests, so to speak, a focus on everything, not on the most serious or readily provable drug offenses. Logically, U.S. attorneys in states with legalized marijuana would be compelled by the Sessions memo to start prosecuting individuals in the now-mainstreamed pot business. The result would be a sensational — and likely grueling — cultural, political and legal crisis.

Related: California AG: Sessions’ new war on drugs ‘crazy and stupid’

Such a crisis would probably be more severe than the social changes being wrought by the widespread liberalization of marijuana law at the state level. Moreover, it’s unclear what benefits the Sessions policy would deliver. We have learned the hard way that mandatory minimums, including well-intended but ultimately perverse measures like “three strikes” laws, reduced crime to a degree while increasing prison populations — and the size and impact of prison culture — to a greater degree.

Beyond the downside of paying year after year to lock inmates in brutal hothouses that leach criminality back into the law-abiding world, so-called mass incarceration has also helped ensure that convicted Americans who do emerge from prison ready and willing to re-enter society frequently face virtually insurmountable hurdles.

These considerations should carry additional weight at a time when many Republicans favor a targeted focus — with a more forgiving spirit — on opioid addiction, and when the vast majority of Democrats continue to warn that racially and ethnically disproportionate sentencing cannot only destroy communities but distort and destabilize American society at large.

Although the cultural and legal status of drug use is unsettled today, a broad consensus is forming around moving carefully away from the crackdown mentality toward a less destructive, reactive and impersonal justice system. Changing that will prove harder and more costly than Attorney General Sessions seems to believe.