Beginning July 1, it will be legal for Oregonians to use marijuana recreationally.
With the change in the law, there are questions about how police officers will determine a driver's level of impairment from using the drug.
While there is a measurable legal limit for alcohol use, the same is not true for use of marijuana.
Critics of marijuana legalization have argued the result will be more impaired drivers on Oregon roadways.
Crash statistics from Washington, which legalized marijuana in 2012, however, show very little change since the law changed, with fatal crashes decreasing every year since 2005.
Only 9.2 percent of all fatal crashes in 2013 involved drivers who tested positive for THC, the chemical in marijuana responsible for its psychological effects. Only 2.8 percent involved drivers who tested positive only for THC.
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