"The individual state analyses suggest that the size of the effect varies by state".
Those differences remained in Colorado and Washington even after searchers dropped following pot legalization.
Although the first-of-their-kind studies landed at differing - and critiqued - conclusions, researchers and industry members alike did come to a consensus on one aspect: More research is needed.
By examining data from the U.S. Fatality Analysis Reporting System, researchers compared the number of traffic fatalities from 2009 to 2015 in Colorado and Washington to auto crash-related deaths occurring in eight other states that do not allow recreational marijuana.
Now, states have found it hard to determine how high is too high when around the steering wheel.
"The combined-state analysis shows that the first three states to legalize recreational marijuana have experienced more crashes", said Matt Moore, senior vice president of the Highway Loss Data Institute.
"In Colorado about a 14% increase, in Washington a 6% increase and about a 4% increase in unanticipated crashes in the state of OR", he said.
That study, published by the American Journal of Public Health published, found that compared with eight states where marijuana is not legal, Colorado and Washington saw no significant increase in motor vehicle fatalities from 2009 to 2015. Adjacent states with similar fluctuations in claims were also used for comparison. It's worth noting that Nevada, part of the control group, legalized recreational marijuana in November 2016.
However, legalizing marijuana is still met with hesitation by some in power such as Attorney General Jeff Sessions.
"I believe it would be unwise for Congress to restrict the discretion of the Department to fund particular prosecutions, particularly in the midst of an historic drug epidemic and potentially long-term uptick in violent crime", Sessions said in the letter.
The Highway Loss Data Institute has initiated a large-scale, case-control study in OR to further delve into how legalized marijuana might be affecting the risk of vehicle crashes with injuries, Moore said, adding that his organization will continue to research this topic.
One of the big bullet points that anti-pot legislators consistently cite as a reason to keep marijuana illegal is the potential increase in the number of stoned drivers on our nation's roads. According to data from the Highway Loss Data Institute (HLDI), that's exactly what's happening.
In previous studies, research was mostly conducted under more controlled conditions.
"It is important that governments and businesses continue to educate the public about the danger of impaired driving - whether it is by cannabis, alcohol or other substances - as well as the laws that prohibit it", he said.