Since the legalization of recreational cannabis in Colorado, the policy debate about pot has shifted from whether it should be legal to how to regulate stoned driving. Despite the current legal limit of THC concentration in the blood (5 nanograms THC to 1 milliliter of blood), the issue has remained controversial due to the limitations of current testing methods and a lack of consensus as to what concentrations actually establish a presumption of impairment.
These limitations arise from two major realities:
- In many cases (particularly among chronic users), THC remains detectable in blood and urine tests (often at high levels) long after the intoxicating effects of cannabis have worn off.
- Until recently, very few studies had been done to determine what concentrations truly impair driving. Of the studies that attempted this, most were funded by government agencies with an implicit mandate to depict marijuana as at least as dangerous if not more dangerous than alcohol. As a result, they tended to conclude that very low concentrations were sufficient to cause impairment.
As a result of these knowledge gaps, popular skepticism abounds over the validity of the current legal limits. This skepticism is well illustrated by a Colorado jury’s recent acquittal of a woman, finding her fully capable of driving safely despite being nearly four times over the legal limit.
Simply put, there is little hard science to support the presumption that having a specific amount of THC in the blood causes impairment (as compared to alcohol, which has very predictable effects at certain levels). Even if there were, currently available testing technologies cannot identify how recently someone last smoked cannabis. Lawmakers will continue to wrangle over the per se limits until a true scientific consensus emerges. However, it may soon be possible to address the problem of how recently a person last smoked.
New Testing Method Coming
Several manufacturers are in a race to develop the first breath screening device for cannabis. Hound Labs of California claims to have made a major breakthrough that could bring such a product to the market in the near future. One of the device’s key innovations is purported to be the ability to distinguish between recent and chronic use. While in itself it will not change the game in terms of per se limits, it will hopefully change the conversation. From the linked Fortune Magazine article:
“’Right now the standards are completely arbitrary. I would argue that they are useless,’ Hound Labs Chief Executive Mike Lynn told Reuters, noting that existing tests cannot determine whether a person smoked an hour ago or 12 days earlier.
’Our ability to measure THC in breath really should shift the national dialogue from one about simply detecting if THC is in someone’s body to a conversation where standards can be developed that reflect actual impairment,’ said Lynn.”
It is hoped that the ability to test for more recent usage will not only give law enforcement better ability to determine whether a person is actually under the influence of cannabis at the time of testing, but also provide additional data to inform the debate about what concentrations (combined with timing) actually impair driving. This sort of information would assist in both clearing up the scientific fog surrounding impairment levels and in simplifying enforcement. However, it is not yet a reality. It remains to be seen how the technology will develop, and as it does, there will certainly be issues of technical malfunction, methodology, and human error to grapple with, as there is with breath-alcohol testing today. In any event, this product may soon become the best available technology at law enforcement’s disposal to test for driving under the influence of cannabis.
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If you have been charged with a DUI or DUI-D, you need the best legal representation you can get. The attorneys at the Tiftickjian Law Firm devote their practice to these issues and strive to be among the most knowledgeable in the field. We are on the cutting edge of the legal and scientific developments relevant to defense of DUI, and we are widely recognized as among the best DUI defense attorneys in the state. Contact us today for a free consultation.