The pot lobby is at it again. December 2014, Paul Armentano, NORML’s Deputy Director issued a press release entitled, “Evidence Fails to Support Proposed DUI Impairment Levels for Cannabis.” This in and of itself is nothing new. Researchers have known for years that blood levels of THC bear only a slight relationship to impairment levels (see Dec 12 blog “What level of THC in blood causes driving impairment?”) More to the point, it has long been known that a 5 ng/ml THC legal per se limit is a poor idea that is not based in science (see Aug 26 2013 blog “What THC Limits do Toxicologists Recommend?”)
What we find most interesting in Armentano’s press release is that is was based upon a NHTSA publication entitled “Understanding the Limitations of Drug Test Information, Reporting, and Testing Practices in Fatal Crashes.” In that document, the comment that Armentano based his release upon was incidental. The actual thesis of the NHTSA publication was to caution people to not rely upon NHTSA’s FARS (Fatality Analysis Reporting System) reports to understand prevalence or trends of drugged driving. This is an important thesis with tremendous policy ramifications.
Researchers frequently use FARS reports to try to understand drugged driving prevalence or trends (see Feb 11, 2014 blog “Recent Marijuana-Impaired Driving Studies.”) They even reach conflicting conclusions, depending upon how they analyze the data. This is not too surprising, since FARS was never designed to capture drugged driving data competently, as described in the above blog. It is helpful to see that NHTSA is aware of the FARS limitation and is cautioning people to not infer too much from its flawed database.
What’s most troublesome is that FARS continues to be used as a source database simply because there are no other options. Drugged driving, with a few localized exceptions, is not otherwise measured. Most states never issue DUID citations, but only issue DUI citations covering impairment by alcohol, drugs, or a combination of alcohol and drugs. No effort is typically made to determine what portion of DUI citations are caused by drugs.
Recognizing this, Colorado has spent hundreds of thousands of dollars to identify “gaps” in its knowledge of the impact of marijuana legalization. They will likely spend millions more in studies, meetings, and publications. They may even do something worthwhile like adopt California’s recent statute, which separates DUI-alcohol citations from DUID citations. But don’t count on it.
Armentano’s press release may effectively divert people’s attention away from NHTSA’s thesis to something he wishes to highlight. After all, the technique of redirection works when dealing with stubborn children. Why wouldn’t it work for policy makers?