Since marijuana legalization, highway fatalities in Colorado are at near-historic lows
Since Colorado voters legalized pot in 2012, prohibition supporters have warned that recreational marijuana will lead to a scourge of “drugged divers” on the state’s roads. They often point out that when the state legalized medical marijuana in 2001, there was a surge in drivers found to have smoked pot. They also point to studies showing that in other states that have legalized pot for medical purposes, we’ve seen an increase in the number of drivers testing positive for the drug who were involved in fatal car accidents. The anti-pot group SAM recently pointed out that even before the first legal pot store opened in Washington state, the number of drivers in that state testing positive for pot jumped by a third.
The problem with these criticisms is that we can test only for the presence of marijuana metabolites, not for inebriation. Metabolites can linger in the body for days after the drug’s effects wear off — sometimes even for weeks. Because we all metabolize drugs differently (and at different times and under different conditions), all that a positive test tells us is that the driver has smoked pot at some point in the past few days or weeks.