With marijuana legal for recreational use in both Washington and Oregon, we're beginning to collect good data about its impacts on the highway. Still, with no field test comparable to an alcohol breathalyzer, officers find it difficult sometimes to definitively detect a driver under the influence of marijuana.
That's led some people to suggest that, if you can't tell, it's not a problem. But it's not as simple as that. In Washington, where recreational marijuana has been legal since 2012, fatal crashes involving the drug have doubled. (We have less data from Oregon, which legalized recreational use in 2015.)
We do know that alcohol and marijuana affect drivers differently: Alcohol-impaired drivers are more likely to speed and overestimate their skills. Marijuana-impaired drivers have difficulty trying to handle several tasks at once or when confronted with something unexpected. When alcohol and marijuana are combined, they're worse than either one alone.
The bottom line: No impairment is good impairment, whatever the source. Check out this video to see what you can do to help keep our roads safer.