Study Suggests Tests for Marijuana Impairment Not Based in Science

Even as Illinois lawmakers consider a bill that would, for the first time, provide a marijuana intoxication standard for charges of driving under the influence (DUI), a new study claims that the foundation for such standards is seriously flawed. The study even went so far as to suggest that setting legal limits of THC in a driver’s blood has no scientific basis and that comparing the effects of alcohol and marijuana on a driver’s ability to operate a vehicle safely is not an apples-to-apples comparison.

BAC and THC Levels

Across the country, a driver found to have a blood-alcohol content (BAC) of .08 is considered to be under the influence, as decades of research have supported a relationship between BAC levels and impairment. With the increase in legalized use of marijuana, including recreational use in several states and medical use in about two dozen, including Illinois, lawmakers and law enforcement officials have been looking for a similar way to relate marijuana impairment to a quantifiable standard.

Thus far, six states have enacted laws that base charges of DUI for marijuana on the levels of THC—the chemical in marijuana that produces the effects of the “high”—found in the driver’s blood. Similar measures are being considered in a number of other states, with one in Illinois expected by many to be passed soon. The Illinois law would set a DUI standard of 5 nanograms per milliliter of blood, while others around the country vary from state to state.

Troubling Research

The AAA Foundation for Traffic Safety, an offshoot of the American Automobile Association, released a study this month that challenges the idea that a “quantitative threshold” can be effectively used to determine a driver’s level of impairment. Reviewing more than 5,000 case reports, the study found that quantitative analysis of THC levels would have misclassified a substantial number of drivers, either as impaired or as not impaired when a Standardized Field Sobriety Test (SFST) showed otherwise. In other words, many who failed the SFST would have been under the legal limit, while many who passed the SFST would have been well above the legal limit.

The Foundation recommends training law enforcement officers to detect driver impairment rather than relying on number-based standards that are not scientifically valid. It remains to be seen how, if at all, the study will affect public policy in the states with existing standards and those who are considering enacting them.

Charged With Drugged Driving?

If you are facing charges of driving under the influence of alcohol or drugs, you need an attorney who is ready to fight for you. Contact experienced Joliet criminal defense lawyer Jack L. Zaremba today to schedule your free consultation. He will meet with you to discuss your case and help you find a resolution that protects your rights and your future.

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