Is there marijuana testing for driving under the influence (DUI)?

There is no system of standardized marijuana testing for DUI.

Ever since marijuana was legalized, I have been concerned about testing for driving under the influence of weed. The first lesson I learned about marijuana was the difference between thumb-sized West Coast joints and pencil-thin East Coast joints. Much later, I have personally learned about the effects of greater levels of THC. I passed out after taking only two tokes of robust joints.

Overall, while several methods exist to test for marijuana impairment, none are as straightforward or reliable as those used for alcohol. This complexity poses significant challenges for law enforcement and legal systems in addressing marijuana-related DUIs effectively.

In Virginia, driving under the influence of marijuana is illegal. This is true in scores of other states that have legalized this drug.

Before anyone gets behind the wheel, know it is illegal in Virginia to drive under the influence. This includes marijuana, using marijuana while operating a motor vehicle, or while traveling as a passenger. A first-time offense could lead to:

One year in jail and/or a fine up to $2,500
$250 mandatory fine
Loss of driver’s license for one year

Additional offenses may result in more severe fines, jail time, and loss of driving privileges. The consequences for driving high are serious because the dangers of marijuana-impaired driving are serious; driving while high is a hazard to everyone who shares the road. Think of others and your own well-being.

Though scores of states have changed their laws regarding marijuana, it is still illegal everywhere to drive impaired by the drug.

Think twice before driving high.

National Highway Traffic Safety Administration, part of the U.S. Department of Transportation helped change the perception of drunk driving by making the phrase “Friends Don’t Let Friends Drive Drunk” standard, and now it’s time to spread the message about the dangers of using marijuana and driving.

NHTSA has partnered with the Ad Council to launch the drug-impaired-driving prevention campaign, If You Feel Different, You Drive Different. Together, we hope to change the cultural conversation around driving after using marijuana to make it as socially unacceptable as driving drunk.

According to studies, marijuana can slow your reaction time, impair judgment of distance, and decrease coordination, which are essential when you’re behind the wheel of a vehicle.

In recent years, drug-impaired driving has become a major highway safety issue. According to a NHTSA study, from 2007-2013 there was a 48 percent increase in weekend nighttime drivers who tested positive for tetrahydrocannabinol (THC ) — the chemical responsible for marijuana’s psychological effects.

Here are some tips for getting home safely.

If you are high on any marijuana or any other impairing substance, don’t drive.

Pass the keys to a sober driver who can safely drive you to your final destination. It is never okay to drive while impaired by any substance.

Take the keys away from a friend who is about to drive while impaired by drugs and arrange to get them home safely. Don’t worry about offending someone — they’ll thank you later.

National safety organizations and the Ad Council have launched the “FeelDifferentDriveDifferent.org” campaign. The site is a resource to help people make intelligent driving decisions. It is designed to remind people about the dangers and illegal nature of drug-impaired driving.

Testing for marijuana impairment while driving is challenging and lacks the precision seen in alcohol testing. Unlike alcohol, which can be easily measured with a breathalyzer, marijuana’s effects are more complex and variable.

Current Testing Methods

Blood Tests: These measure the concentration of THC, the psychoactive component in marijuana, in the bloodstream. However, THC can remain in the blood long after the effects have worn off, making it an unreliable indicator of current impairment.
Saliva Tests: Used to detect recent marijuana use, these tests can show THC presence for 8 to 24 hours after use. However, they can result in false positives and are not fully reliable for determining impairment.
Field Sobriety Tests (FSTs): These assess physical and cognitive functions but are not sensitive enough to detect marijuana intoxication reliably.
Officer Observations: Law enforcement may rely on visible signs of impairment, such as erratic driving or physical symptoms, but these are subjective and can vary widely between individuals.

Challenges

Variability in Effects: Marijuana affects individuals differently, and factors such as method of consumption and tolerance levels complicate testing.

Lack of Consensus: No universally accepted THC level correlates with impairment, making legal standards difficult to establish. Overall, the lack of a standardized system complicates the prosecution and defense of marijuana DUI cases.

Marijuana significantly impacts driving ability in several ways:

Cognitive Impairment

Marijuana use affects key cognitive functions essential for safe driving:

Attention and focus: It impairs a driver’s ability to concentrate on the road and surrounding traffic situations.
Decision-making: THC slows the ability to make quick decisions while driving.
Memory: Short-term memory impairment can affect navigation and recall of traffic rules.
Perception: It distorts perception of time, speed, and distance.
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Physical Effects

Marijuana also impacts physical abilities crucial for vehicle operation:

Reaction time: Slows reflexes and response to sudden changes or hazards.
Coordination: Impairs motor skills needed for steering and pedal control.
Balance: Affects overall body control and stability.

Driving Behavior Changes

Studies have observed specific changes in driving behavior under marijuana influence:

Reduced speed: Drivers tend to drive slower, possibly as a compensatory mechanism.
Lane control: Increased likelihood of lane departures and weaving.
Following distance: Tendency to increase distance from the vehicle ahead.
Overtaking: Decreased attempts to overtake other vehicles.

Duration of Impairment

The effects of marijuana on driving can last longer than many users realize:

Smoking marijuana may impair driving skills for 4.5 to 8 hours.
Edible marijuana products can affect driving for 8-12 hours.

Increased Crash Risk

While the exact relationship is complex, studies indicate:

Marijuana use is associated with an increased risk of being involved in a car crash.
The combination of marijuana and alcohol has an additive or even multiplicative effect on impairment.

It’s important to note that, unlike alcohol, there’s currently no standardized level of THC that definitively indicates impairment, making it challenging to enforce and measure marijuana-impaired driving.

Given these effects, it’s crucial for safety that individuals avoid driving under the influence of marijuana.

Charlie Leocha

Charlie Leocha is the President of Travelers United. He has been working in Washington, DC, for the past 14 years with Congress, the Department of Transportation, and industry stakeholders on travel issues. He was the first consumer representative to the Advisory Committee for Aviation Consumer Protections appointed by the Secretary of Transportation from 2012 through 2018.

Is there marijuana testing for driving under the influence (DUI)?

There is no system of standardized marijuana testing for DUI.