The results of this study have caught the attention of Washington state and Colorado authorities.

A recent Columbia University study shows over the last decade,  driver fatalities stemming from driving under the influence of marijuana have risen from 4% in 1999 to 12% in 2010.

The study  examined data from six different states that automatically run toxicology tests on deceased drivers. The states are California, Hawaii, Illinois, New Hampshire, Rhode Island and Virginia.   Other states do test but often only if the circumstances appear to require a toxicology exam.

Drugged drivers also accounted for 28% of the fatalities found in the study, up from 16%.  Of those 28%, 12% were from pot.  Dr. Guohua Li, who oversaw the study, said an alcohol-impaired driver is 16 times more likely to get in a crash, but a driver impaired by both alcohol and marijuana is 24 times higher than a sober person.