Drivers who have ignition interlocks installed in their vehicle may wonder if the device detects marijuana. The answer is no — the devices are developed to detect only the presence of alcohol in someone’s breath and is unable to detect the presence of marijuana. However, drivers who attempt to blow marijuana smoke into their device should know that this could trigger a positive BrAC reading on your device, which could lead to a lockout or other penalties. Remember, you are responsible for every positive sample registered in your device, regardless of the source.
Ignition interlock requirements for drug-impaired driving
Several states that have legalized marijuana also require drivers to install an ignition interlock if charged with drug-impaired driving. While the devices do not detect alcohol — officers can perform roadside tests to determine the amount of THC in a driver’s system. IIDs are still recommended for use by researchers due to studies demonstrating strong correlations between drinking alcohol and smoking marijuana.
A 2016 U.S. National Survey of Drug Use and Health (NSDUH) found that several key trends among people who co-use alcohol and marijuana
- For people who drink alcohol, 10–27% also smoke marijuana
- For people who have an alcohol addiction, 23–58% also smoke marijuana.
- 20 percent of young adults aged 18–29 smoke marijuana, and 50–70 percent 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.
IIDs and Safety
These findings demonstrate that requiring the use of ignition interlock devices for drivers convicted of drugged-impaired driving could prevent them from driving drunk. Currently, 10 states and Washington, D.C., have legalized marijuana for recreational use for adults over the age of 21, and 33 states 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.
Marijuana Use When Driving
States that have legalized the drug 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.
The bottom is line is 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.