Maybe the message should be don't smoke and drive.
Turns out that people who use marijuana before driving are nearly twice as likely to cause an accident as those not under the influence.
That's according to a Canadian analysis of several previous studies.
Researchers found drivers who had used marijuana within three hours of beginning to drive had nearly double the risk of causing a collision, especially those that were fatal.
Marijuana is the most widely used illegal drug worldwide and rates of its use in drivers are increasing.
Copyright 2012 KPHO. All rights reserved. The Associated Press contributed to this report.