IN 2013, Eric Holder, then the attorney-general, issued a memo telling prosecutors to avoid charging certain defendants—such as non-violent offenders who were not members of drug gangs—with offences that would hand them long prison sentences. On May 11th, Jeff Sessions rescinded that policy, suggesting that prosecutors “pursue the most serious, readily provable offence.”

Mr Sessions’s memo constitutes the first big criminal justice effort by the Trump administration to get tough on drugs. It had already made it clear that it would be tougher on drug offenders than Barack Obama's administration. In particular it has set its sights on creeping legalisation to legalise marijuana: nine states have authorised its sale for recreational use. Sean Spicer, the White House spokesman, has suggested the administration will pursue tougher enforcement of federal laws against use of the drug. And on April 5th, Mr Sessions released a memo explaining that his new Task Force on Crime Reduction and Public Safety will “undertake a review of existing policies in the areas of charging, sentencing, and marijuana to ensure consistency with the Department's overall strategy on reducing violent crime and with Administration goals and priorities.” In a recent meeting with reporters, Mr Sessions warned that “experts are telling me there's more violence around marijuana than one would think.”

The administration argues that the legalisation of drugs and lax enforcement leads to violent crime. But the evidence on marijuana points in the opposite direction: thanks to medical marijuana laws that have legalised the drug, fewer people are getting killed in the drug trade.

Evelina Gavrilova Takuma Kamada and Floris Zoutman, economists, looked at the impact of the passage of medical marijuana laws in American states bordering Mexico. They find that legalisation reduces the level of homicides by 11% and robberies by 26%—and that the drop in the murder rate is linked to a decline in drug-law and juvenile-gang related homicides of over one third. The effect is particularly large in counties along the Mexican border. The researchers also find that the price of cocaine rises while cocaine seizures drop. They suggest drugs cartels are losing out to legal competition in the marijuana market and are trying to make up for lost profits through raising prices on other product lines—depressing demand as a result.

At a time where the epidemic of opioid addictions—many the result of legal prescriptions—is one factor behind stalling gains for life expectancy in America, the costs of drug use should not be underplayed. Research by Hefei Wen from Emory University and colleagues into the effect of medical marijuana laws suggests they increase consumption of the drug. Marijuana use can also cause respiratory conditions, increases the risk of vehicle accidents and may be associated with abuse of other substances according to a report by the National Academies of Sciences, Engineering and Medicine.

That said, marijuana appears to be a lot less carcinogenic than tobacco and a safer drug than alcohol—especially in terms of the violence related to consumption. And even if Mr Sessions's concern is the violence surrounding production and sale rather than use, legalisation reduces that problem. The positive experience of states that have legalised marijuana may be one factor behind growing public support for the reform country-wide—up from 36% in 2005 to 60% in 2016 according to Gallup polling. And for an administration promoting America First, replacing illegal imported production with licit home grown pot should be a clear policy win.