New study finds alcohol may impair driving more than pot

The research showed that alcohol had an effect "on the number of times the car left the lane and the speed of the weaving" but marijuana users showed no signs of impairment. The study did find that cannabis users "with blood concentrations of 13.1 ug/L THC" did show increases weaving among drivers. The researchers equated the weaving as comparable to someone with a blood alcohol level of .08 -- the legal limit for drivers in most U.S. states.  According to Time, the legal limit for drivers on pot is 5 ug/L (in states where such use is legal), namely Colorado and Washington. 

The study’s principal investigator, Dr. Marilyn Huestis, noted that the important takeaway from the study was that they looked “at the concentration of THC in the driver’s system while they were driving,” and most anyone who is arrested for DWI is tested hours after they've been taken into custody.

The other fact that they discovered was the pot and alcohol become more potent when used together. According to the study, drivers who used both were “weaving within the lanes.” This is because smoking pot while drinking increases the THC absorption and makes the high the user is having more intense, Time reports.

Read more at Time.