Driving Under the Influence of Marijuana in Virginia

Virignia driving while under the influence laws are outlined in VA Code 18.2-266, which criminalizes DUI, DWI, and DUID as misdemeanor and felony criminal offenses. Virginia classifies first offense and second offense cases as class 1 Misdemeanor crimes, punishable by up to 1 year in jail, a fine between $250.00 and $2,500.00, between 12-36 months of driver’s license suspension, mandatory alcohol education classes, and probation. Third offense cases are penalized as felony crimes, with at least 90 days in jail and up to 5 years in prison, permanent revocation of your driving privileges, amongst the other standard DUI penalties. But, unlike alcohol, marijuana THC levels in the blood do not reliably indicate intoxication.

THC Levels Unreliable Indicators of Marijuana Intoxication

Researchers for the National Institute of Justice investigated how marijuana affects skills required for safe driving and found that biofluid levels of THC did not correlate with field sobriety test performance or marijuana intoxication, regardless of how the cannabis was ingested.

The researchers “concluded that, although THC has been proven to affect areas of the brain that control movement, balance, coordination, memory, and judgment, – skills required for safe driving – THC levels in biofluids were not reliable indicators of marijuana intoxication for their study participants.”

Results from the toxicology tests showed that the levels of all three targeted cannabis components (THC, cannabidiol, and cannabinol) in blood, urine, and oral fluid did not correlate with cognitive or psychomotor impairment measures for oral or vaporized cannabis administration.

Nonetheless, the study participants’ cognitive and psychomotor functioning were negatively impacted after all oral and vaped doses of cannabis except for the lowest vaped dose, which contained 5 mg THC. For vaped THC doses over 5 mg, peak cognitive and psychomotor effects were observed zero to two hours after administration and returned to baseline after four hours. For oral THC doses, cognitive and psychomotor effects were observed one hour after administration and peak effects were seen about five hours after administration. Participants’ cognitive and psychomotor functioning returned to baseline eight hours after oral administration.

THC levels in biofluids are not reliable indicators of marijuana intoxication.

Field Sobriety Tests Unreliable Indicators of Marijuana Intoxication

The National Institute of Justice researchers reported that the standard field sobriety tests used in Virginia, the one leg stand, walk and turn, and modified Romberg balance tests, were not sensitive to cannabis intoxication for any of the study participants. Thus, field sobriety tests are not reliable indicators of marijuana intoxication.


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