mLIVE.com reported a fatal crash in Oklahoma that killed six teenage girls in March 2022 is another example of the growing concern around marijuana-impaired driving. The 16-year-old driver’s blood tested positive for THC. The concentrations were so high that investigators concluded she was “likely still experiencing acute impairing cannabis effects.” Experts noted that pinpointing marijuana-induced impairment remains notoriously difficult because THC levels do not rise and fall in a predictable way, unlike alcohol.
Across the United States, laws surrounding cannabis-impaired driving vary widely. Some states have set “per se” THC limits similar to blood-alcohol thresholds while other states impose zero-tolerance policies that criminalize any detectable amount of THC. Because frequent marijuana users can test positive for THC long after any effects have worn off, current testing limits can not clearly create a correlation between THC levels and actual impairment.
Testing limits also force officers to rely on old tactics such as performing roadside balance and coordination tests. Drug Recognition Experts (DREs) are at times called in to conduct more thorough 12-step assessments. Although DRE evaluations help secure thousands of convictions nationwide, their validity is under increasing scrutiny. Many medical and legal experts argue that DREs simply provide subjective police opinions rather than scientifically reliable evidence. Consequently, courts in several states have ruled that DRE officers can not testify as experts.
