Drivers in Virginia can be charged with drinking and driving for being impaired or having a blood alcohol concentration (BAC) of 0.08% or higher. When it comes to marijuana, there is no clear line to say whether a driver is impaired based on a drug test. Other states have a specific threshold to determine whether a driver is per se driving under the influence of marijuana.

“Under the Influence” in Virginia

Virginia Code Section 18.2-266 (ii) makes it unlawful to drive or operate a motor vehicle while "under the influence of alcohol." Under the influence means a person has consumed enough alcohol to “affect his manner, disposition, speech, muscular movement, general appearance or behavior, as to be apparent to observation.”

However, there is also a per se violation if the driver has a BAC of 0.08% or higher. This means that a driver can be charged with a DUI if his or her BAC is over the limit even if there are no signs that the driver is impaired. 

Drug Impairment in Virginia

When it comes to DUI and drugs, a driver is in violation of the DUI laws if any narcotic drug or intoxicant impairs the driver's ability to drive or operate the motor vehicle safely. There is also a per se limit for certain drugs, including:

• 0.02 milligrams of cocaine per liter of blood,
• 0.1 milligrams of methamphetamine per liter of blood,
• 0.01 milligrams of phencyclidine (PCP) per liter of blood, or
• 0.1 milligrams of 3,4-methylenedioxymethamphetamine (MDMA) per liter of blood.

Marijuana Per Se Limit

Virginia has not set a per se limit for marijuana or testing for THC, an active ingredient in marijuana. Other states have different approaches to marijuana limits, including making it illegal to drive with any amount of a prohibited drug or metabolite.

This can be a problem for drivers who have used marijuana because metabolites or evidence of marijuana use can be present in the blood long after the effects of marijuana have worn off.

Only a few states set a threshold limit for the presence of THC. This may allow for a permissible inference that the driver was impaired or a per se violation, similar to a per se alcohol DUI. Colorado, Montana, Illinois, and Washington have set limits for marijuana DUI as a 5 nanogram threshold of THC. Nevada and Ohio set their per se marijuana DUI at 2 nanograms of THC.

Virginia Prosecutor Calls for Marijuana Standards

According to a WVTF report, the Commonwealth's attorney in Albemarle, VA is seeking a per se THC impairment standard for Virginia. The Commonwealth's attorney was prosecuting a case where a garbage truck driver was hit by an Amtrak train and the prosecutor believed the driver was under the influence of THC.

According to the prosecutor, the driver had a THC level of 6.6 nanograms. However, the judge dismissed the THC impaired maiming charge based on the unreliability of the evidence linking THC to impairment. A law to set a limit for THC in drivers was passed by the house in 2006 but the senate never took up the vote.

Charlottesville Drug DUI Attorney

With or without a threshold limit for drugged driving and marijuana, a chemical blood test is not always accurate. When the machines are not properly cleaned, maintained, calibrated or the operator contaminates the test sample, it can result in an inaccurate measure of the driver's blood. If you were arrested for impaired driving in Virginia, talk to your Charlottesville DUI defense attorney about your case challenging marijuana DUI charges. Contact attorney me today for a free consultation.