Opponents of the marijuana DUI standard have doubts that impairment by marijuana and impairment by alcohol can by measured similarly. It is understood that the effects of cannabis on psycho-motor abilities is correlated to dosage, however lawmakers cannot agree on how to appropriately measure impairment due to issues relating to residual neuropyschological effects.
Colorado is one of 16 states that allows medical use of marijuana, and on November 6, 2012, Colorado Amendment 64 will be on the ballots, which is an amendment to Article 18 of the state constitution that would allow for a progressive marijuana drug policy. Essentially, personal use and regulation of marijuana would be allowed for adults over the age of 21 if Amendment 64 is passed.
Opponents of the THC-limit worry that medical marijuana users may be wrongly accused if the bill is passed. “We risk convicting people of an impaired infraction when they’re not actually impaired,” said Michael Elliott, executive director of the Medical Marijuana Industry Group. Another possible concern could be detection of cannabinoids even if one is not an active user of marijuana. In the Journal of Forensic Science, a study by Morland et al. (1985) shows that passive inhalation of cannabis smoke can be detected in blood and urine, with THC concentrations being detected as high as 6.3 ng/mL.
These are issues that must be confronted by lawmakers especially in a state that allows for medical use and may be on its way to legalization of marijuana.