NC officials raise concerns about marijuana-impaired driving enforcement

Detecting marijuana impairment in drivers is posing a challenge to law enforcement — one that could strain North Carolina agencies if the state legalizes the drug, according to officials and policy analysts advising a state advisory council.

Marijuana remains 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. 

The North Carolina Advisory Council on Cannabis in April recommended that lawmakers consider a regulated adult-use cannabis market, arguing the state should replace its largely unregulated THC marketplace with a comprehensive regulatory framework.

Several proposals to legalize marijuana have been introduced in recent years, including measures targeting hemp-derived THC products and proposals to establish medical cannabis access, but none have cleared both chambers of the Republican-controlled state legislature.

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. There is no agreed-upon roadside test or legal threshold for marijuana impairment.

Current testing methods can detect tetrahydrocannabinol, or THC, the main psychoactive compound in cannabis, in a driver’s system. But THC can remain detectable for weeks after the effects have worn off.

“All it will show is the presence,” Matt Thomas, an Arkansas law enforcement official and drug-impaired driving specialist, told members of the North Carolina Advisory Council on Cannabis last week. The bipartisan group was created by Stein to develop recommendations on cannabis regulation.. 

“What that shows is recent usage,” Thomas said. “It does not show impairment.”

Cannabis impairment doesn’t consistently correlate with THC levels in the body. Frequency of use, tolerance and method of consumption all affect how a person responds, and no established threshold exists comparable to alcohol’s blood-alcohol content standard, according to Thomas. 

Instead, enforcement of marijuana impairment relies on field observations, standardized sobriety testing and specially trained Drug Recognition Experts, known as DREs.

North Carolina has about 175 certified DREs among roughly 34,000 law enforcement officers statewide, according to Thomas..

The lack of DREs is most acute in rural areas, where many departments operate with fewer than 20 officers, particularly in western North Carolina. Officials also noted that officers with specialized certifications are often recruited by larger agencies offering higher pay.

“There’s not enough and we’re not currently ready to take this on,” Roxboro Police Chief David Hess said in an interview.

Michael Baca-Atlas, an associate professor of family medicine and psychiatry at the UNC School of Medicine, said cannabis impairment is fundamentally different from alcohol intoxication — and far less predictable.

Alcohol impairment tends to follow a measurable, dose-dependent pattern, while cannabis affects coordination, judgment and reaction time in ways that vary widely based on the individual, Baca-Atlas said.

“The bottom line is you cannot equate THC levels with impairment in the same way you can with alcohol,” Baca-Atlas said in an interview.

Rural enforcement 

Geography adds another layer of difficulty to enforcement.

Gillian Schauer, executive director of the Cannabis Regulators Association, said smaller jurisdictions often lack the personnel to send officers for advanced training, while certified experts may be hours away from the scene of a traffic stop.

“The mobilization and getting DREs positioned throughout the state have been the challenges,” Schauer told the state cannabis council last week.

Impairment evaluations must occur quickly after a stop, and delays can affect investigative outcomes.

“If it takes a long time for a DRE to respond, a long time to get somebody down to the precinct to draw blood, the picture can look very different the longer the time window extends,” she said.

A typical alcohol-related DUI investigation can take 30 to 45 minutes, while drug-impaired driving cases often take significantly longer.

"It's imperative for public safety that the legislators provide funding for additional training and support for our judicial officials, including law enforcement,” Hess said.

Top legislative leaders, including House Speaker Destin Hall and Senate leader Phil Berger, didn’t respond to requests for comment on the advisory council’s recommendations.

The advisory council is expected to issue a final report later this year.