In 2014, they published an analysis of opioid-related deaths from 1999 to 2010 and found that fatalities were lowered in states that had passed medical cannabis laws.[12][13] The study suggested that access to medical marijuana could reduce the need for prescription painkillers.[14] The study later came under scrutiny when a 2019 study found that states that introduced medical marijuana laws between 2010 and 2017, the number of opioid overdoses increased.[15] Cunningham noted that the conflicting findings necessitate more research into the impacts of medical marijuana, which is currently difficult because of regulations around cannabis.