Some states impose limits on THC concentrations per se. Nevertheless, several states currently apply limits per se to determine marijuana-impaired driving, typically 5 ng/ml of THC, although in some states the limit is as low as 1 ng/ml. Driving a vehicle with THC concentrations in the blood exceeding the limit per se is illegal. Colorado applies an “appropriate inference standard” whereby any THC concentration greater than 5 ng/ml can be calculated as an indication of impairment. (Other states have a zero-tolerance policy for THC — any THC content is prohibited.) Are people really being arrested for driving while impaired by marijuana? In addition to general impairment laws, there are two basic laws that states use to deal with drug-impaired driving: Setting a limit on what should be allowed now is more of a policy decision than a science, said Paul Larkin, a senior researcher at the Heritage Foundation who has frequently written about the problem. States that have set limits have chosen a figure that seems satisfactory to a large number of people. Thirty-three states have “effects-based” driving under the influence of marijuana laws that criminalize a person for driving when they are truly impaired, which is determined based on all available evidence. These include footage or testimonials about how the person was driving, the results of a 12-step analysis by a drug detection expert to determine if the person smelled like marijuana, and blood test results for THC — marijuana`s main psychoactive ingredient. However, seventeen states have passed “per se”, “zero tolerance” or “rebuttable presumption” laws criminalizing drivers if they have THC or metabolites in their blood or if they have a certain amount. But, as the AAA Foundation for Road Safety concluded, the laws themselves are “arbitrary and not backed up by science.” 1 Individuals react differently to tetrahydrocannabinol, the active ingredient in marijuana, making it nearly impossible to set legal limits that estimate roughly equal levels of driving disability. Some people drive without measurable impairment, while others are unable to work with the same amount of THC in their blood. A key issue raised in many studies on the effects of marijuana impaired driving and its risks is the “persistence of THC.” Unlike alcohol, THC levels in a user`s body may not be an accurate indication of impairment. Since 2012, 18 states and the District of Columbia have passed laws allowing anyone over the age of 21 to possess and use marijuana, subject to certain restrictions.
Most of these states also have or are in the process of developing regulations for a commercial market to support the sale of recreational marijuana. Many experts agree that part of the solution is a device that can measure a driver`s amount of THC, a device that is portable and inexpensive enough for police to buy and take away like breathalyzers do. But alcohol metabolizes in the lungs and liver, which makes it possible to test breath, unlike THC. Even if there was a portable reader, it doesn`t mean states can find a fair limit on the amount of THC in the blood. I use medical marijuana, can I still be arrested for not being able to drive? In Michigan, there is no legal THC limit to prove that a person is guilty of driving marijuana. For alcohol, the limit is uniform: a blood alcohol level greater than 0.08%. But there is no standard limit for THC, the psychoactive compound in marijuana. And even in places where a limit is introduced, it`s not clear whether exceeding the limit is a deficiency, experts say. For example, there is evidence that user impairment can also result in limited “compensatory defensive” driving, where a user drives more carefully to compensate for impaired motor function – but this can only mitigate the impairment of some abilities and may not apply to non-chronic users. The frequency of collision claims appears to have increased.
Insurance records show an increase in claims under collision coverage paid for damage to a guilty insured driver`s own vehicle, according to HLDI`s latest analysis. Retail legalization in Colorado, Nevada, Oregon and Washington was associated with a 4% increase in collision damage frequency compared to other western states from 2012 to 2019. The 4% decrease is slightly lower than the 6% increase seen in a previous study from 2012 to 2018. More and more states are passing laws allowing the use of marijuana for medical and/or recreational purposes, raising concerns about marijuana use.