The authors review literature showing that marijuana impairs driving, increasing the risk of being involved in a car accident and that these risks are further enhanced when combining marijuana with alcohol.
Links
[1] http://www.nih.gov/news/health/jun2014/nida-04.htm
[2] http://rethinkpot.org/tags/health
[3] http://rethinkpot.org/tags/car-accident%2A
[4] http://rethinkpot.org/tags/impairment
[5] http://rethinkpot.org/tags/research