A study that recently appeared in the Journal of the American Medical Association shows a significant decrease in opiate overdoses in states that have adopted and implemented medical marijuana laws compared to states that have not.

The authors showed that although opiate overdoses rose in states without medical marijuana laws during 2009-2010, they dropped by approximately 25 percent in states with medical marijuana laws during that same period. While these data cannot show a causal relationship between the passage of medical marijuana laws and a decrease in opiate overdoses, they are consistent what medical marijuana patients have been saying for years, that they are consciously choosing medical cannabis over pharmaceutical drugs.

The finding of this study has important policy implications that demand a closer examination of the possible expansive benefits of medical marijuana laws to both individual and public health as well as what components of those laws make them more or less effective at improving overall health.

Many of the headlines about this study stated that overdose deaths were significantly reduced in the 23 states that allow access to medical marijuana. In fact, the study only evaluated 10 of the 23 states—those states with laws that were implemented between 1999 and 2010: Alaska, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Mexico, Rhode Island, and Vermont.

These state medical marijuana laws all have features in common in addition to their time of implementation that are not true of all the state medical marijuana laws: They all allow patients and caregivers to cultivate marijuana for medicinal use ensuring patients continued access to marijuana. They all allow for marijuana to be used for a significant number of medical conditions. They all allow for medical marijuana to treat and manage pain. They all allow patients to access to the whole plant, to marijuana containing both THC and CBD, and to ingest marijuana through a variety of methods, including smoking and vaporizing.

By comparison, many of the states that have adopted medical marijuana laws more recently—Illinois, Minnesota, New York—have taken much more restrictive approaches that severely limit the number of patients eligible for the programs, the ability of those patients to access marijuana, and the types of marijuana those patients may use, and even the ways that patients may ingest marijuana.

Concerns about increasing access to marijuana may have driven some of these more restrictive states to take such a limited approach. However, we may eventually discover that it is increased access to marijuana by a larger number of patients that is the driver of a number of health benefits beyond what was contemplated when the medical marijuana laws were originally designed.

What this groundbreaking study shows that there has been a significant reduction in overdose death in states that have adopted robust medical marijuana laws with comprehensive patient access. Whether the same positive benefit will bear out in states with much more restrictive medical marijuana laws remains to be seen.

The findings of this new study are not surprising. They are consistent with previous research findings that marijuana and opiates work well together to relieve pain, and that the use of marijuana allows patients to use less opiates, reducing their risk of overdose. Patients have been reporting this behavior for years.

A 2009 study of 350 medical cannabis patients found that nearly three-fourths of them reported using marijuana as a substitute for prescription drugs, with better symptom management and less risk of withdrawal as the primary reasons. These results have been replicated with several thousand patients, and the results were the same.

While these data cannot show that access to medical marijuana causes a reduction in opiate overdoses, we do know that medical marijuana patients are engaging in substitution and that rates of opiate overdoses fell in states with medical marijuana laws that provide a significant number of patients with meaningful access to marijuana.

With prescription drug overdoses now the number one cause of accidental death in the U.S., that is nothing to scoff at.

Amanda Reiman is the manager of marijuana law and policy for the Drug Policy Alliance. Tamar Todd is the director of marijuana law and policy for the Drug Policy Alliance.

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