The number of fatal cannabis-associated MVAs may be increasing. One Colorado study suggests that the number of fatal MVAs in which the driver was cannabis positive has increased with legalization, particularly with the change in federal policy in 2009; no such trend was seen in states without medical marijuana laws (55). However, given that the number of fatal MVAs has been on the decline in Colorado since 2004 (55), the perceived increase in marijuana-positive MVAs may merely reflect the general increase in cannabis use in Colorado over the study period. Further, as discussed above, the finding that a driver is marijuana positive at the time of a MVA does not indicate that marijuana was the cause of the accident (64).
