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Marijuana DUI

Is it Legal to Drive After Using Marijuana?

Although marijuana use and possession will soon be legal in Illinois, the laws governing cannabis DUIs have not changed. In other words, it will remain illegal to drive or be in physical control of a motor vehicle while under the influence of cannabis.

Medical cannabis has been legal in Illinois since 2014 and the recreational use of marijuana will become legal on January 1, 2020. Under the new law, it will be legal to possess and use marijuana products in Illinois within certain limits as to the amount of marijuana or THC concentration (THC is the chemical in marijuana that causes its psychoactive effects).

When can I be Arrested for Driving Under the Influence of Marijuana?

In Illinois, there are generally 2 ways that you can be charged with driving under the influence of marijuana.

1) Driving while under the influence of marijuana alone or in combination with other drug(s), meaning that the person is incapable of safely driving (in most cases, based on a police officer’s observations); and/or

2) Driving with an excess concentration of THC in the person’s body. In Illinois, it is illegal to drive with a THC concentration of 5 or more nanograms in a person’s bloodstream or 10 or more nanograms in any other bodily substance (e.g. saliva or urine) within 2 hours of driving or being in physical control of a motor vehicle. A nanogram is simply a measurement of the substance in a person’s body.

However, in Illinois, the law prohibiting a person from driving with an excess amount of THC in their system does not apply to a person holding a valid medical marijuana card.

What are the Penalties for a Marijuana DUI?

The potential penalties for a cannabis-based DUI are essentially the same as the penalties for an alcohol-based DUI. Penalties can range from court supervision to prison time, depending on the defendant’s prior record (prior DUIs and other criminal history) and aggravating factors present in the case (i.e. an accident with injuries).

A first offense Cannabis DUI is usually charged as a Class A misdemeanor, which carries a maximum penalty of up to 12 months in jail and a $2,500.00 fine plus mandatory court costs. At a minimum, if found guilty or after a plea of guilty, the defendant would be required to complete an alcohol/drug evaluation, risk education classes and attend a victim impact panel.

A conviction for a cannabis DUI will result in a driver’s license revocation. This license penalty is separate from the statutory summary suspension, which is automatically imposed 46 days after you are served with a Notice of Statutory Summary Suspension. The suspension will be as follows:

  • Refuse chemical testing: 12-month summary suspension
  • Fail chemical testing: 6-month suspension
Medical Use of Marijuana and DUI

The medical marijuana law went into effect on January 1, 2014, which allows those with certain medical conditions to legally possess and use marijauna to alleviate the symptoms associated with those conditions.

These include conditions such as cancer, arthritis, glaucoma, multiple sclerosis, Parkinson’s disease, spinal cord injuries, brain injuries, limb pain and post-concussion syndrome. For a complete list of conditions see this article.

Those persons who have a qualifying medical condition and wish to use medical marijuana may apply for permission to use it. Upon approval, they are granted a Medical Cannabis Registry Card. This card gives the patient immunity from state or local laws prohibiting the possession or use of marijuana, provided that the patient complies with the law’s requirements.

A person who holds a Medical Cannabis Registry Card is also granted immunity from the marijuana DUI law, which prohibits driving or being in physical control of a motor vehicle at or above the THC limit. However, the law does not grant the person immunity if their use of marijuana has caused impairment which makes them unable to drive safely.

In Illinois, a person under investigation for DUI may be asked to submit to certain physical field performance tests by the police officer, known as standardized field sobriety tests (SFSTs). These tests may include the horizontal gaze nystagmus test, walk and turn test, and one leg stand test. Under Illinois law, there is no penalty if the driver refuses one or more of these tests or fails these tests.

However, registered medical cannabis users must submit to these tests when requested by a law enforcement officer if the officer has a reasonable suspicion that the person is driving under the influence of marijuana. If the person refuses or fails the tests, they are subject to a summary suspension of their driving privileges. Persons who are not registered medical marijuana users have no obligation to submit to these tests and there is no penalty for refusing or submitting to and failing testing.

A registered user who refuses field sobriety tests faces the following driver’s license consequences:

  • Refuse testing: 12-month summary suspension
  • Fail testing: 6-month suspension

Medical marijuana users are not eligible for a monitored device driving permit (MDDP) during the period of the suspension. Additionally, registered marijuana users who hold a commercial driver’s license (CDL) are also subject to a 12-month CDL disqualification (and a lifetime loss of CDL in the case of a second suspension) if they refuse or fail testing. The disqualification applies to a CDL holder whether they were driving a commercial or non-commercial vehicle at the time of the offense. Other drivers who hold CDLs are not subject to disqualification for refusing or failing field sobriety tests.


Those who plan on engaging in the recreational or medical use of marijuana must remember that it is still illegal to drive under the influence of cannabis.

Additionally, the DUI consequences for those who obtain a medical marijuana registered users card are potentially more severe than for those who are recreational users, including the obligation to submit to (and pass) standardized field sobriety tests, the denial of a MDDP during the period of a summary suspension, and a disqualification for a CDL holder for refusing or failing physical field performance testing. Again, these consequences do not apply to recreational marijuana users who do not hold a medical registered user card.

Contact Our Cannabis-DUI Attorneys

The Cannabis DUI attorneys at The Davis Law Group, P.C. have studied and identified many issues under the current DUI cannabis laws. Attorney Larry A. Davis has been a representative of the Illinois State Bar Association in the drafting of the DUI cannabis laws as well as having extensively lectured and written on the new laws. Contact us today to arrange a consultation. We practice throughout the Chicago Area including Cook County, Lake County and DuPage County. Let us put our knowledge and experience to work for you.

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