Anti-pot proponents falsely claim that liberalized marijuana policies are associated with rising opioid abuse, but the scientific data says just the opposite.

According to a study published last year in the Journal of the American Medical Association Internal Medicine, the enactment of statewide medicinal marijuana laws is associated with significantly lower state-level opioid overdose mortality rates. Investigators conducted a time-series analysis of medical cannabis laws and state-level death certificate data in the United States from 1999 to 2010—a period during which 13 states instituted laws allowing for cannabis therapy.

“States with medical cannabis laws had a 24.8 percent lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws,” researchers reported.

Specifically, they found that overdose deaths from opioids decreased by an average of 20 percent one year after the law’s implementation, 25 percent after two years and up to 33 percent by years five and six.

“[O]ur results suggest a link between medical cannabis laws and lower opioid analgesic overdose mortality,” investigators concluded.

A separate study published this month by the National Bureau of Economic Research, a non-partisan think-tank, shows that the JAMA data is not anomalous. Researchers from the RAND Corporation and the University of California, Irvine assessed the impact of medical marijuana laws on problematic opioid use, as measured by treatment admissions for opioid pain reliever addiction and by state-level opioid overdose deaths.

“[S]tates permitting medical marijuana dispensaries experience a relative decrease in both opioid addictions and opioid overdose deaths compared to states that do not,” they reported.

Researchers found that women over the age of 40 showed the most significant decrease in problematic opioid use.

The notion that chronic pain patients will choose pot over opiate pain relievers is hardly surprising. According to a series of clinical trials overseen by the University of California, San Diego, the inhalation of whole-plant cannabis is safe and efficacious in the treatment of various types of neuropathy—a type of pain that is poorly managed by opiates. Moreover, clinical data published in 2011 in the journal Clinical Pharmacology & Therapeutics showed that cannabis administration significantly augments the analgesic effects of opiates in patients with chronic pain.

The idea that cannabis can act as an adjunct—or, in some cases—as a substitute to opiates is welcome news.

Overdose deaths involving opioid analgesics have increased dramatically over the past decade. While fewer than 4,100 opiate-induced fatalities were reported for the year 1999, by 2010 this figure rose to over 16,600 according to an analysis by the U.S. Centers for Disease Control.