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Kevin O'Flaherty

In this article, we will discuss driving under the influence of marijuana and ask the questions “can I smoke marijuana while driving?”, “is it legal to drive after smoking marijuana?”, “what is the current law in Illinois concerning DUIs and THC”, “what is the process for proving DUI of marijuana”, and “what to do if you’ve been charged with a marijuana-related DUI.”

With 2020 came the legalization of recreational marijuana use in Illinois and with it a slew of confusion and concern from both the public and law enforcement. While the information on the topic is easy to find, more niche concerns such as what we address in today’s article can sometimes be hazy. 

First, let’s talk about whether it is legal to smoke marijuana while driving. 

The answer to this question is simple: NO. It is absolutely illegal to smoke marijuana or most any other drug while operating a vehicle. And yes, it is also illegal for a passenger to smoke marijuana inside a moving vehicle. A person can transport marijuana in their vehicle if it is the legal amount, properly sealed and placed at an appropriate distance from the driver and passengers. For more information on where it is legal or illegal to smoke marijuana in Illinois check out New Illinois Law Legalizing Marijuana in 2020 FAQ.

Can I Drive After Smoking Marijuana? 

Here is where things get a little murky. The best answer is it may depend on timing. Ultimately, law enforcement can always put a driver through a field sobriety test and if they fail it’s bad news. Similarly, when operating a motor vehicle in Illinois you automatically give consent to a breathalyzer and/or blood/urine test under the Implied Consent Law, if the officer feels he or she has probable cause. A person could conceivably still be charged with a DUI even when not “high” due to THC metabolites still being present in the blood hours or days after use. This is an unlikely scenario in the first place because again, typically the officer would first have to have probable cause to order the blood test. But it is legally possible.

Current laws in Illinois Regarding Marijuana DUIs

If we drill down into the specifics of the law we see a similar situation to DUI of alcohol. First off, Illinois DUI laws are very strict and certainly not in favor of the offender. As mentioned previously, if you have a driver’s license you give consent to be tested. However, Illinois does set the bar at 5 nano-grams or more of THC per milliliter of blood to be charged with a DUI from a lab testing standpoint. Again for more information regarding marijuana laws in Illinois check out New Illinois Law Legalizing Marijuana in 2020 FAQ

What is the Process for Proving a Marijuana DUI?

When someone is pulled over under the suspicion of DUI they may initially be put through a field sobriety test. These are physical performance tests that challenge balance, vision, memory, etc and are standardized. However, these tests are specific to alcohol and not generally used as evidence for DUI of marijuana. Breathalyzer tests are also used only in the case of alcohol and can’t accurately measure the nano-liter levels of THC associated with marijuana DUI charges. Additionally, there are no roadside blood or urine test options for law enforcement, and while the use of saliva testing for THC is increasing, it is at most in its experimental phase with regards to consistent and accurate THC measurement against an established baseline. Still, if the police officer feels it is warranted they can ask the driver to submit to a blood and/or urine test at the appropriate location. 

What Should I Do if I’ve Been Charged with a Marijuana DUI?

If an individual fails a chemical test for THC levels, is charged with a DUI, and it is his or her first offense they can lose their license for six months to one year, be fined $2,500.00 and possibly face imprisonment of up to one year. 

With a second offense, you’re looking at three to five years loss of license, mandatory jail time or community service, substance abuse counseling, and likely further fines.

If you are charged with a marijuana-related DUI it is advisable to get into contact with a qualified DUI attorney. He or she will advise you on next steps. Bottom line, don’t drive high, and if you’re not sure, still don’t drive.

Disclaimer: The information provided on this blog is intended for general informational purposes only and should not be construed as legal advice on any subject matter. This information is not intended to create, and receipt or viewing does not constitute an attorney-client relationship. Each individual's legal needs are unique, and these materials may not be applicable to your legal situation. Always seek the advice of a competent attorney with any questions you may have regarding a legal issue. Do not disregard professional legal advice or delay in seeking it because of something you have read on this blog.


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