DUI Defender

As law enforcement steps up its efforts to investigate and subsequently arrest more drivers for driving under the influence we are beginning to see an increase in driving under the influence of drugs cases, or more commonly called, “drugged driving.” We continue to see cases with Ambien and other sleep aids more commonly that those involving marijuana but we are seeing an increase in marijuana as well.

Marijuana cases cause specific problems for law enforcement as there are no standards for quantifying the blood or urine concentration that will result in impaired driving. It is difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects. Concentrations of parent drug and metabolite are very dependent on pattern of use as well as dose. The parent drug is the actual drug consumed while the metabolyte is the processed, but still measurable residue from the drug. Unfortunately, many involved in law enforcement are unaware that the metabolyte is not active and is not currently affecting/impairing the test subject.

In fact, the National Highway Traffic Safety Administration (NHTSA) concedes, “It is inadvisable to try and predict effects based on blood THC concentrations alone, and currently impossible to predict specific effects based on THC-COOH concentrations. It is possible for a person to be affected by marijuana use with concentrations of THC in their blood below the limit of detection of the method. Mathematical models have been developed to estimate the time of marijuana exposure within a 95% confidence interval. Knowing the elapsed time from marijuana exposure can then be used to predict impairment in concurrent cognitive and psychomotor effects based on data in the published literature.”

While more studies need to be conducted on the effects of marijuana on driving, NHTSA, itself states that “some drivers may actually be able to improve performance for brief periods by overcompensating for self-perceived impairment.” For information see the NHTSA article about Marijuana and human performance.

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