NHTSA, the federal highway safety people, compared cannabis to alcohol in a 2015 study.
Result: Drinking small amounts increases chances for a crash 7 times. Drivers with THC in their system were no more likely to crash than sober drivers.
(TRUCE does NOT advocate driving under the influence of ANY substance.)    

See full article – A New Study Just Explored The Difference Between Driving Drunk vs. Stoned