Unlike testing for alcohol, breath testing technology does not yet exist for cannabis. However, this type of technology is growing ever closer. The principal problem is that the technology must detect recent cannabis use and additionally prove that the cannabis in one’s system impaired the driving.
The problem arises because cannabis may be detected in one’s body long after the effects of the drug have worn off. THC, the active ingredient in cannabis may remain on the breath for two to three hours after use. Nonetheless, a person may have THC detected on their breath, yet be unaffected by the drug.
Lawmakers in several states have advocated for cannabis to be regulated like alcohol with a established “per se” levels at which drivers would be considered impaired if operating or in physical control of a motor vehicle. However, according to a CNN Business report published in January 2020, “Minimal research exists on how cannabis affects driving. Although some of the most notable cannabis research has occurred in Israel, there are longstanding complaints that federal research in the US has been hindered by low-potency and poor-quality cannabis samples.”
Research on breath testing for cannabis and other drugs continues to progress. Until such time as a reliable and accurate alternate measure is developed, though, blood testing, which may require a search warrant, appears to be the most frequently used test for drugs other than alcohol.
About the Author: Steven Oberman has been licensed in Tennessee since 1980, and successfully defended over 2,500 DUI defendants. Among the many honors bestowed upon him, Steve served as Dean of the National College for DUI Defense, Inc. (NCDD) and currently serves as chair of the National Association of Criminal Defense Lawyers DUI Committee. Steve was the first lawyer in Tennessee to be Board Certified as a DUI Defense Specialist by the NCDD.
He is the author of DUI: The Crime & Consequences in Tennessee, updated annually since 1991 (Thomson-West), and co-author with Lawrence Taylor of the national treatise, Drunk Driving Defense, 8th edition (Wolters Kluwer/Aspen). Steve has served as an adjunct professor at the University of Tennessee Law School since 1993 and has received a number of prestigious awards for his faculty contributions. He is a popular international speaker, having spoken at legal seminars in 30 states, the District of Columbia and six foreign countries. After being named a Fulbright Scholar, Steve was honored to teach as an Adjunct Professor at the University of Latvia Law School in the capital city of Riga, Latvia during the Spring Semester of 2019.