NOTE: This article features new content to account for Illinois legal changes once Public Act 101-363 became state law. Since August 9, 2019, this Act amended various aspects of the state DUI statutes as recreational use marijuana became legal in Illinois.
In Illinois, the offense of driving under the influence (DUI) can be based on consumption of alcohol, drugs, or even prescribed medication. Some refer to this as drugged driving, as opposed to drunk driving. Most versions of DUI in Illinois are prosecuted under the same statute, 625 ILCS 5/11-501.
Section 11-501 of the Illinois vehicle code statute says a person can be guilty of DUI in seven ways, prohibiting a person from driving while:
(1) the alcohol concentration in the person’s blood, other bodily substance, or breath is 0.08 or more based on the definition of blood and breath units in Section 11-501.2;
(2) under the influence of alcohol;
(3) under the influence of any intoxicating compound or combination of intoxicating compounds to a degree that renders the person incapable of driving safely;
(4) under the influence of any other drug or combination of drugs to a degree that renders the person incapable of safely driving;
(5) under the combined influence of alcohol, other drug or drugs, or intoxicating compound or compounds to a degree that renders the person incapable of safely driving;
(6) there is any amount of a drug, substance, or compound in the person’s breath, blood, other bodily substance, or urine resulting from the unlawful use or consumption of a controlled substance listed in the Illinois Controlled Substances Act, an intoxicating compound listed in the Use of Intoxicating Compounds Act, or methamphetamine as listed in the Methamphetamine Control and Community Protection Act; or
(7) the person has, within 2 hours of driving or being in actual physical control of a vehicle, a tetrahydrocannabinol concentration in the person’s whole blood or other bodily substance as defined in paragraph 6 of subsection (a) of Section 11-501.2 of this Code. Subject to all other requirements and provisions under this Section, this paragraph (7) does not apply to the lawful consumption of cannabis by a qualifying patient licensed under the Compassionate Use of Medical Cannabis Program Act who is in possession of a valid registry card issued under that Act, unless that person is impaired by the use of cannabis.
A charge for drunk driving is prosecuted under section (a)(1), where the driver’s blood or breath alcohol concentration is 0.08 or higher, or section (a)(2), where there is no chemical test of 0.08 or more, but the driver was intoxicated.
The remaining sections of the Illinois DUI statute – (a)(3), (a)(4), (a)(5), (a)(6), and (a)(7) – concern driving while intoxicated on drugs.
Illinois Drugged Driving Law
If a person drives while taking prescribed medication that causes dizziness, drowsiness, poor balance, poor depth perception, or otherwise impairs his ability to drive, that person is guilty of DUI. It is not a defense that the medication was legal, purchased over the counter, or prescribed. See 625 ILCS 5/11-501(b).
The issues in a trial are different for cases involving legal drugs, such as prescribed medication or over-the-counter pills, versus cases involving illegal drugs, such as cocaine, heroin, ecstasy, LSD, or any other drug.
When it comes to illegal drugs, the prosecution can prove the defendant is guilty of DUI only if it can prove the defendant violated sections (a)(3), (a)(4), or (a)(5).
In prosecutions involving legal drugs, such as prescriptions, the defendant is guilty only if the evidence shows they were operating a motor vehicle while:
(3) under the influence of any intoxicating compound or combination of intoxicating compounds to a degree that renders the person incapable of driving safely;
(4) under the influence of any other drug or combination of drugs to a degree that renders the person incapable of safely driving;
(5) under the combined influence of alcohol, other drug or drugs, or intoxicating compound or compounds to a degree that renders the person incapable of safely driving.
625 ILCS 5/11-501
A person is guilty of Illinois DUI based the effects of prescription medication if the medication causes him to be unable to drive safely. The issue in trial is whether the person could reasonably and safely drive a car.
- An analysis of a DUI case involving prescription medication should involve these questions:
- Was the driver involved in an accident? If so, was the driver the cause of the accident, or were they unable to avoid the accident that was caused by another person’s negligence?
- Did the driver commit any traffic violations? If the driver did get a ticket, were any of the moving violations of such a nature that someone was endangered?
A prosecution for driving under the influence of illegal drugs can be prosecuted based on section (a)(4):
(4) under the influence of any other drug or combination of drugs to a degree that renders the person incapable of safely driving.
But unlike prescribed medications, a prosecution for DUI based on illegal drugs can also be brought under the per se law. Section (a)(6) is the per se violation of the DUI statute, and it applies like the legal limit of 0.08 alcohol concentration. It says it is a violation to drive if,
(6) there is any amount of a drug, substance, or compound in the person’s breath, blood, other bodily substance, or urine resulting from the unlawful use or consumption of a controlled substance listed in the Illinois Controlled Substances Act, an intoxicating compound listed in the Use of Intoxicating Compounds Act, or methamphetamine as listed in the Methamphetamine Control and Community Protection Act.
Here, the prosecution does not need to prove that the person was incapable of safely driving. Rather, it is the presence of any amount a controlled substance or methamphetamine in the person’s blood, breath, or urine that results in a DUI.
This means that a positive test for cocaine, heroin, morphine, peyote, LSD, mushrooms, barbituric acid, amphetamine, methamphetamine, pentazocine, ketamine, methaqualone, PCP, speed, or ecstasy can result in DUI charges.
The Illinois laws against possession of controlled substances and methamphetamine are found at 720 ILCS 570/102 and the schedules of controlled substances are listed under sections 204 through 218. Cannabis is defined in 720 ILCS 550/3.
Since Illinois legalized marijuana for recreational use in 2020, there are different rules for operating a motor vehicle while under the influence of cannabis. Illinois law now provides specific levels for intoxication or impairment based on marijuana, if a driver registers a blood or breath test in excess of certain THC concentrations.
