Can a Car Breathalyzer Detect Weed (Marijuana)?

Ignition interlocks (IID), also known as car breathalyzers, are devices that help prevent you from driving under the influence of alcohol. An IID requires you to pass a breathalyzer test before allowing you to start your car. If you are wondering if an interlock can detect use of weed, also known as marijuana, cannabis, and pot, the answer is NO. Ignition interlock devices are only designed to check your Breath-Alcohol Content (BrAC) and cannot detect weed presence in your body.

Although your car breathalyzer interlock device cannot detect marijuana in your breath, it can detect the presence of smoke. Blowing smoke into the breathalyzer can lead to a lockout and penalties. Remember, you are responsible for every breath positive sample registered in your device, regardless of the source. Smoke could register as an error on your device.

How Interlock Devices Prevent Drug-Impaired Driving?

You may be required by law to install an IID into your vehicle if you have been charged with drug-impaired driving. Several states mandate the installation of an IID even though it does not detect marijuana. Research studies demonstrate a strong correlation between marijuana smoking and alcohol consumption.

According to a 2016 U.S. National Survey of Drug Use and Health, several findings were related to the co-use of alcohol and marijuana.

• Alcohol users were 10-27% more likely to smoke marijuana
• Alcohol addicted users were 23-58% more likely to also smoke marijuana
• 20% of young adults aged 18–29 smoke marijuana and 50-70% of them also drink alcohol
• People who co-use alcohol and marijuana are more likely to use the substances at the same time
• People who are addicted to marijuana are more likely to have an alcohol use disorder

These findings demonstrate that requiring the use of car breathalyzers for drivers convicted of drug-impaired driving could prevent them from driving drunk. Currently, 11 states and Washington, D.C., have legalized marijuana for recreational use for adults over the age of 21, and 33 states plus D.C. have legalized medical marijuana. Because of this legalization, the National Highway Traffic Safety Administration is working with Congress to find an effective way to measure how the drug impairs drivers and to prevent drug-impaired driving.

States that have legalized marijuana have seen an increase in the number of marijuana-related crashes and violations. For example, vehicle crashes investigated by Maryland State Police nearly doubled from 2017 to 2018, and driving violations related to marijuana jumped by almost 40 percent. In Colorado, fatal crashes have increased by 74 percent since 2013 — the year marijuana was legalized. State police believe marijuana has been a major factor in the increase.

Safety is Always Important

Smoking marijuana affects a person’s driving abilities, and you can get arrested for a DUI if found driving under the influence of the drug. Driving while intoxicated or impaired poses a serious danger to you and other road users.