States that have legalized medical marijuana may soon find themselves in greater conflict with the US Department of Justice, as it seeks to end the country’s “historic drug epidemic” (“Sessions seeks to prosecute cannabis dispensaries,” June 14).

Recent science tells us that reducing access to medical marijuana does not lead to declines in opioid use. In fact, it is very likely that the opposite is true.

Numerous studies published in influential medical journals have found that greater availability of marijuana may reduce the frequency and amount of opioid consumption. Medical marijuana patients report that they substitute marijuana for alcohol, prescription medications, and illicit drugs, in part to reduce adverse effects such as craving and withdrawal. And in states that have legalized medical marijuana, there are lower rates of death from opioid overdoses.