RICHMOND, Va. – THC breathalyzers are frequently discussed as a potential means to identify drivers under the influence, particularly as Virginia approaches the establishment of a retail cannabis market. However, significant questions about their effectiveness persist.
Currently, there is no standardized and widely approved THC breathalyzer test available. Researchers, including former Virginia Commonwealth University professor Emanuele Alves, have been working on developing an effective device, supported by a grant from the National Institute of Justice for a prototype.
Research Developments
Alves’ research received considerable media attention in 2023, though she has since departed from VCU and was unavailable for comment. In a recent publication, Alves indicated that a patent has been filed for her future prototype aimed at roadside cannabis testing.
Michelle Peace, a forensic science professor at VCU with expertise in toxicology, notes that while there have been advancements in THC breathalyzer technology, the traditional markers used to assess recent alcohol use and impairment do not apply to THC. “For alcohol, we have established a threshold of 0.08% blood alcohol concentration as the impairment level,” stated Peace. “For THC, we cannot define an equivalent cutoff without understanding its implications on impairment.”
She further elaborated that such metrics do not clarify the timing of THC consumption. “Without context, a number might not indicate recent use; it could reflect consumption hours earlier,” said Peace. This complexity arises from the differing metabolic processes of alcohol and THC.
Limitations of Current Testing Methods
Field sobriety tests, along with THC levels, have proven unreliable in accurately determining marijuana intoxication, according to research from the Research Triangle Institute International. Toxicology tests may identify the presence of cannabis, but they do not effectively measure cognitive or psychomotor impairment.
Complicating matters, cases of impaired driving frequently involve poly-drug use. A 2024 analysis by the Virginia DMV highlighted that 30% of individuals with a blood alcohol concentration of 0.08% or higher also tested positive for cannabis. However, the DMV also emphasized that cannabis legalization does not lead to an increase in individuals driving under the influence. It may, instead, foster more careful monitoring of cannabis-related driving infractions.
Public Safety Campaigns
Chelsea Higgs Wise, executive director of Marijuana Justice, advocates for informed public health campaigns to enhance road safety. “Traditional ‘no drug driving’ messaging has frequently failed to resonate,” she remarked. “We need to empower adults to make safer choices and encourage discussions around responsible cannabis use.”
Wise suggested strategies to mitigate impaired driving, emphasizing the importance of not driving immediately after consumption, particularly with edibles that have delayed onsets. Community engagement is crucial, such as encouraging individuals to seek alternative transportation.
Concerns have also been raised regarding the efficacy of Drug Recognition Experts (DREs), who are trained to identify drug impairment during traffic stops. Matthew Demlein, public relations coordinator for the Virginia State Police, noted that 21 DREs currently serve in Virginia after undergoing approximately 80 hours of training. DREs are called when questions arise about a driver’s intoxication, leading to potential charges.
“We are investing substantial resources in certifying officers to perform assessments that not even medical professionals can conclusively make,” said Wise, highlighting the complexities of drug impairment evaluations.
Looking Ahead
The Virginia General Assembly has recently passed House Bill 642 and Senate Bill 542, paving the way for a retail cannabis market overseen by the Virginia Cannabis Control Authority. This authority will also be responsible for regulating certain hemp products.
As part of a broader initiative, the Virginia Cannabis Control Authority has launched various campaigns aimed at raising awareness about the dangers of driving under the influence of cannabis. As Jamie Patten, chief administrative officer of the CCA, noted, “Our findings suggest that many Virginians continue to believe cannabis improves driving safety, which is simply untrue.”
The CCA’s “Bad Combinations” campaign aims to emphasize that driving while impaired by cannabis is both dangerous and illegal. The initiative encourages individuals to plan ahead and make responsible choices to ensure safety on the roads.
For more information on driving safety and cannabis-related risks, visit cca.virginia.gov/safedriving.