Marijuana DUI: Driving Under the Influence of Drugs

Most states have legalized medical marijuana for qualifying patients. About half of states have also legalized marijuana for adult recreational use. Marijuana legalization does not make it acceptable or safe to operate a motor vehicle while impaired. Drugged driving is more dangerous when combined with alcohol or other drugs.

Marijuana impaired driving is a challenge to assess accurately, efficiently, or equally. The drug’s effects can vary depending on the individual marijuana user. Drug-impaired driving laws can vary by state. To understand the laws for driving and cannabis use in your state, contact a local DUI lawyer for legal advice.

Effects of Marijuana on Driving

According to the National Highway Traffic Safety Administration (NHTSA), marijuana can slow reaction time, impair motor skills, and hurt a driver’s ability to multitask. If a driver’s ability to safely operate their vehicle is impaired by marijuana, the driver can face drugged driving charges.

Law enforcement can measure the influence of alcohol by blood alcohol content (BAC) using a breath test, blood test, or other chemical tests.

However, there is no widely used breathalyzer for tetrahydrocannabinol (THC), the intoxicant in marijuana. But metabolites of marijuana can remain in the body for much longer than alcohol.

Different drivers can also respond differently to levels of THC. “There are significant problems for clients who use marijuana so often that they don’t feel affected by five nanograms at all. They feel like they’re completely and totally fine, but are actually over the legal limit,” says Anna Goykhman, a criminal defense attorney in Everett, Washington, who has handled several DUI cases. 

State Laws for Marijuana Use and Impaired Driving

Drunk driving and drugged driving laws vary by state. States have different laws for driving under the influence of drugs (DUID), including:

• Zero-tolerance laws. These policies prohibit any detectable amount of THC, metabolites, or other illicit drugs. Drivers testing positive for any amount of THC or related metabolites can face charges for driving under the influence of marijuana, even if they are driving safely.
• Per-se limits based on the concentration of THC. This is similar to the 0.08 percent blood alcohol concentration limit in most states. Drivers with a concentration over the per se limit can face DUI criminal charges. Per se limits for THC can vary by state, generally one to five nanograms per milliliter of blood. In states like Colorado, there is a permissible inference of impairment for drivers with five or more ng/ml. However, drivers can rebut this inference by showing they were not impaired.
• General impairment laws. The majority of states rely on general impairment-based laws for drugs, including marijuana, opioids, and even over-the-counter drugs. The laws simply state that it is unlawful for a person who is under the influence of any drug to drive a vehicle. For a drug DUI conviction, the police officer must assess the actual impairment of a driver.

For example, New York has no per se cannabis law. Marijuana-related DUI cases turn on whether one drove while impaired and if marijuana caused their impairment. “In part, that is a subjective determination based on the observations of a police officer,” says Jeremy Saland, a criminal defense attorney at Saland Law in New York City.

Circumstances Leading to a Marijuana DUI

There are a number of circumstances when a driver may come to be suspected of impairment due to marijuana, including:

• A traffic stop for a moving violation
• A stop at a DUI checkpoint
• A stop for a vehicle-related issue, such as a broken taillight

A police officer may come to suspect the driver is under the influence from smelling or seeing pot or paraphernalia in the car. The police can also observe the driving patterns or appearance of the driver. Any of these can be evidence of impairment.

Jay Tiftickjian, an attorney at the Tiftickjian law firm in Denver, says you should wait at least 12 hours or more to drive after consuming marijuana. “And never keep marijuana in your car. But if you do, keep it in a sealed container in the trunk.”

Testing for the Presence of Marijuana

A citing officer may request assistance from an officer trained as a Drug Recognition Expert (DRE) to further assess a driver’s state. A DRE has training to perform field sobriety tests and examine for specific signs of drug-related impairment. The prosecutor can use the written contemporaneous observations of a DRE as evidence to support a drug-related DUI charge.

“There is no scientifically approved machine that proves THC impairment in the street,” says Karl C. Seman, a New York criminal defense attorney at Grunwald & Seman.

Blood or Urine Tests for the Presence of Marijuana

Testing for the presence of marijuana or other drugs generally requires blood testing or urine tests. The fact that a marijuana marker can remain in a person’s fat cells for up to 30 days after use only complicates matters. “These cases require observational evidence, which is much different than the standard DWI, which is one and done,” Seman says.

If arrested, the driver has a blood test to determine THC levels in their system. Blood tests will also identify alcohol levels and the presence of any illegal drugs. Under the implied consent laws in most states, you may not refuse to submit to chemical testing. There are penalties associated with refusing chemical testing after a DUI arrest.

The Way You Ingest Marijuana Can Impact Its Effects on You

The mode by which one ingests marijuana impacts the drug’s effect. “With THC, there are different forms of consumption — eating, vaping, smoking — and there are different strengths of THC in products,” says William M. Kirk, a DUI attorney at Cowan Kirk Kattenhorn in Kirkland, Washington.

“People who take edibles should be careful. While inhaled marijuana affects your system almost immediately, the full effect of edibles can take up to two hours, can last longer, and can be more potent,” says Steven Epstein, a criminal defense attorney in Garden City, New York.

Disputing Presented Evidence

The presence of THC remains in your blood for as much as two days after smoking or consuming (and even longer in your urine).

There is also no consensus as to what quantity would constitute impairment. As a result, the findings of a blood test don’t conclusively show that a driver was under the influence of the drug at the time they were driving.

After taking the sample, the analysis involves looking for two things:

1. Active THC. “That’s the stuff that’s actually psychoactive at the time of the blood draw and would impair a person’s ability to drive a car,” says Kirk.
2. Carboxy-THC. “That’s metabolized THC that’s no longer psychoactive, but remains in the body for weeks. You can’t tell when it was metabolized—a week ago or between the time of driving and blood draw.”

If you’re arrested for a marijuana DUI case, having a reputable and experienced DUI defense attorney assist you in challenging the evidence of impairment can make a huge difference to the outcome of your case. An attorney can raise challenges as to:

• The appropriateness of the traffic stop
• The conclusiveness of any test-related data
• The manner in which the test itself was conducted and its results handled
• Other procedural issues related to your arrest and the evidence presented

Drug DUI Penalties

Penalties for a DUI conviction for cannabis are generally the same as those for a DUI for alcohol. Depending on state law, penalties for a first offense may include:

• Fines
• Suspended driver’s license
• Possible jail time
• Substance abuse counseling and DUI school

For subsequent convictions, your penalties increase. Many states have long look-back periods to include drug and alcohol DUIs to determine penalties and possible felony charges.

Get Legal Help from a DUI Attorney

If you’re facing DUI drug charges, consult a criminal defense attorney with experience in DUIs as soon as possible. A DUI lawyer will understand marijuana DUI laws and defenses, and many lawyers provide free consultations. Search the Super Lawyers directory to find an experienced DUI attorney in your area.