A blood alcohol content level of .08 is the standard for impairment from alcohol, but now with marijuana legal in so many places the limit for marijuana impairment is very foggy. Maine is considering following Colorado, Washington and Montana who all have legal THC limits set at 5 nanograms. The problem is that research is slim and so far points out that 5 nanograms is so low, that a frequent marijuana smoker can have over 5 nanograms in their system, while not having smoked at all that day. Some say having the limit at 5 nanograms will be a good start, while others are worried about non-impaired drivers being wrongly convicted.
David Boyer, a group member and marijuana legalization advocate leading the push for a 2016 legalization vote in Maine, said it is worth noting that the group did agree on many aspects of the recommendations, but there wasn’t consensus when it came to the science behind determining impairment. He said some group members are concerned that regular marijuana users could be falsely convicted for driving while impaired because they build up a tolerance to THC. A heavy medical marijuana user, for example, could carry a THC level of 5 nanograms per milliliter and show no signs of impairment, he said.