North Carolina officials are considering expanded toxicology testing to help police investigate marijuana-impaired driving cases, including a possible statewide testing model.
Toxicologists told the North Carolina Advisory Council on Cannabis on Wednesday that blood testing can help establish recent cannabis use. Current testing methods can detect tetrahydrocannabinol, or THC, the main psychoactive compound in cannabis, in a driver’s system. But it can’t determine for sure whether someone is intoxicated, since THC can remain detectable for weeks after the effects have worn off.
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Marijuana is illegal in North Carolina. But lawmakers and Gov. Josh Stein have been examining its legalization. Most other states have legalized it for medical use, and about half of the U.S. has legalized recreational use.
Legalization would bring wide-ranging regulatory oversight and enforcement, such as determining when someone is driving under the influence.
Law enforcement officials see challenges with widespread enforcement since there’s no agreed-upon roadside test or legal threshold for marijuana impairment.
As of June, North Carolina had about 175 certified Drug Recognition Experts among roughly 34,000 law enforcement officers statewide. The shortage is particularly challenging for smaller and rural departments.
“There’s not enough, and we’re not currently ready to take this on,” Roxboro Police Chief David Hess told WRAL in June.
On Wednesday, a state cannabis council committee on public safety heard from toxicologists on how they can help.
“Toxicology is not the magic bullet, but the toxicology is the scientific evidence of exposure,” Donna Papsun, a toxicologist with NMS Labs, a private forensic laboratory that already works with law enforcement agencies in North Carolina, told the council.
Papsun said blood is the preferred sample because it provides the best indication of recent cannabis use. But blood should be considered with other evidence, including driving behavior, officer observations, field sobriety tests, and evaluations by what police call “drug recognition experts.”
“All that has to align together in these investigations,” Papsun said.
Testing also goes beyond determining whether cannabinoids are present. Toxicologists said an initial screening identifies a class of drugs, while confirmation testing determines the specific compound and its concentration. The quality of that testing matters because results may be used in court.
NMS told council members that its current turnaround time is about 14 days and that its laboratory could handle more samples. The company works with more than 100 North Carolina law enforcement agencies and said it would be open to a pilot program that could potentially expand statewide.
The company said it has the capacity to perform more laboratory testing but would need additional staff for statewide reporting, interpretation, and potential court appearances.