Are blood or saliva concentrations of delta-9 THC metabolites predictive of impairment?
That’s what a recent article in the Neuroscience and Biobehavioral Reviews journal sought to determine.
The article published data from a meta-regression analysis of 28 studies involving 824 participants.
The biggest takeaway is that neither THC nor THC metabolite concentrations are consistent predictors of impairment. Surprisingly, THC levels in blood, which is the bodily specimen of choice in OWI search warrants in Iowa, showed the weakest correlation.
Iowa law equates the mere presence of inactive metabolites of THC with being under the influence of cannabis. However, the science clearly indicates this is not always true.
It’s time to reconsider our backdoor prohibition against cannabis for OWI.