DUI in Illinois: Laws, Penalties & What You Need to Know After a DUI Arrest

Illinois law makes it a crime for someone to drive while under the influence of alcohol or drugs. Like other states, it sets a legal limit for alcohol concentration in a driver's blood at 0.08 percent, and it also sets a legal limit for THC, the intoxicating substance in marijuana. Chemical testing is used to determine whether a driver violated the legal limits for these substances, but it is also possible for a driver to be charged with driving under the influence (DUI) in Illinois without chemical testing. Anyone found guilty of driving under the influence faces both administrative and criminal penalties.

​Read More:​ Laws & Penalties for a DUI First Offense in Illinois

Some states call it driving while intoxicated, others term it operating a motor vehicle while intoxicated, and still others refer to driving under the influence. But they all mean the same thing: The criminal offense of getting behind the wheel of a vehicle while impaired by alcohol or drugs. In Illinois, the statutes term the crime driving under the influence, and it includes both "per se" violations and impairment violations.

Per se violations are those that set legal limits of the amount of a particular substance in a driver's system. If chemical testing shows that the driver exceeds the legal limit, it is automatically a per se DUI, meaning that no other evidence of impairment is required to obtain a conviction. Other types of DUIs rely on police officer testimony about a driver's ability to operate a motor vehicle. This includes problems with coordination or balance resulting from use of alcohol or drugs that impair the driver's faculties.

All states, including Illinois, have per se DUI statutes for alcohol, setting the blood alcohol concentration (BAC) limit for most drivers at 0.08 percent. That means that if chemical testing shows that the driver's BAC is 0.08 percent or more, they have committed a DUI without further evidence of impairment necessary.

Illinois sets an even lower BAC limit for commercial drivers; their legal BAC limit for alcohol is 0.04 percent. School bus drivers and young drivers (under the age of 21) aren't allowed to drive with any amount of alcohol in their system. That is, their BAC legal limit is 0.00 percent, so they violate the DUI law if they are driving with any discernible alcohol in their system.

Illinois is also among the minority of states that has a per se violation for marijuana use. State law permits individuals over the age of 21 to use cannabis for medical or recreational purposes. But a driver may not operate a motor vehicle while impaired by the use of cannabis. That is, the law sets a legal limit for the amount of tetrahydrocannabinol (THC) in a driver's system.

A driver will be charged with a DUI if a chemical test reveals a THC concentration of five nanograms or more in their blood or 10 nanograms or more in the driver's urine or other bodily substance.

Finally, there is a legal limit of zero for illegal drugs. That is, if a chemical test reveals any discernible amount of any controlled substance in a driver's blood, urine or other bodily substance, they have committed a DUI. Certain types of drugs are defined as controlled substances in the Illinois state codes.

Per se DUIs depend on determining the presence of alcohol or drugs in a driver's body and measuring the amount of those substances. This can only be accomplished by chemical testing; the most common of these are breath, blood and urine testing. Breath tests can determine alcohol, but not drugs in a driver's system.

Drivers – especially those who have been drinking or using drugs – may be very reluctant to take a chemical test and may refuse to do so. For that reason, Illinois has passed an implied consent law. This law provides that all individuals who drive in the state are deemed to have given consent to administer chemical tests when police have probable cause to believe they are driving under the influence of alcohol and/or drugs.

Refusal to undertake chemical testing when requested by law enforcement results in the administrative suspension of their driver's license and driving privileges. This is called a statutory summary suspension.

Can a driver who refuses to take a breathalyzer or chemical test still be convicted of a DUI in Illinois? Yes, they can, but the prosecutor will need to introduce additional evidence to convict them. While it is illegal to drive with a BAC of 0.08 percent or higher in Illinois, it is also illegal to drive while under the influence of alcohol.

Likewise, while it is illegal for an individual to drive with more than the legal limit of THC in their system, it is also illegal to drive under the influence of THC or any drug to a degree that the person is incapable of driving safely. This includes prescribed medication that causes dizziness, drowsiness, poor balance, poor depth perception, or otherwise impairs a person's ability to drive. The fact that the medication was legally prescribed or purchased over the counter is not a defense to this charge.

The role of the prosecutor is different when a DUI charge is based on impairment. They must establish beyond a reasonable doubt that the driver was impaired and unable to drive safely because of consuming the substance. Police or other witnesses can testify as to the driver's behavior behind the wheel, on getting out of the car and during field sobriety tests. Any odor of alcohol or drugs can also be evidence, as is the person's physical appearance, like a red face or dilated pupils.

Any violations of the implied consent laws or the per se DUI statutes are first punished in Illinois administratively, not in the courts. Administrative action does not include imprisonment and is usually limited to license suspension or revocation.

If a driver is arrested for a DUI and refuses to take a chemical test, the police officer confiscates their driver's license and imposes a statutory summary suspension of the license. If the driver does take a chemical breath test but fails it with a BAC level over the legal limit, the arresting officer also confiscates the driver's license as part of a statutory summary license suspension. In either of these situations, the officer gives the driver a receipt that allows them to drive for 45 days following the arrest.

A DUI offender can appeal the statutory summary license suspension by requesting a judicial hearing on the issue. The court will consider only four issues at this hearing:

1. Did the arresting officer follow proper procedures when making the arrest?
2. Was there probable cause for the arrest?
   
3. Did the driver refuse to submit to the chemical test?
4. Was the driver’s BAC level or THC or other drug levels over the legal limit?
   

Assuming the suspension is upheld, the length of time that the license will be suspended depends on the driver's prior record and whether they failed the test or refused to take the test. For example, a first offense results in statutory summary license suspensions of six months for failing a chemical or urine test and 12 months for refusal to take the test. Second offense administrative suspensions are for 12 months for failing a test and 36 months for refusal.

​Read More:​ Third Offense DUI in Illinois: Laws, Penalties & What to Expect

Illinois law sets out strict criminal penalties for driving under the influence of alcohol or other impairing substances. Note that the administrative license suspension applies regardless of whether the driver is charged in criminal court for the DUI and regardless of whether the driver is convicted. That means that even if the driver is not convicted, they still lose their driver's license for at least six months.

But, unsurprisingly, there are additional penalties and more serious ones for those who are convicted of a DUI criminal offense in Illinois. The driver can be sentenced to jail, fined, ordered to perform community service, ordered to enroll in and complete a drug and alcohol program, and will have their driver's license revoked.

Penalties depend on several factors. First, they are greater with each repeat offense. A first offense is subject to less harsh penalties than a second, and a second offense less than a third. In addition, aggravating factors can increase the penalties. For example, a driver whose BAC level tests out at 0.15 percent or higher will get greater penalties than a driver whose BAC is between 0.08 and 0.15 percent.

If the DUI driver has a passenger under the age of 16, this automatically transforms the DUI into a felony, even for first-time offenders.

​Read More:​ Aggravated DUI in Illinois: Definition, Penalties & Next Steps

There are two levels of criminal convictions in Illinois: misdemeanors and felonies. A crime that is a misdemeanor is the lesser offense, and the maximum imprisonment time is one year. A felony is the most serious type of crime, including the worst types of crimes, like murder and treason. Felonies are always punishable by more than a year in prison.

First and second DUI offenses in Illinois are classified as Class A misdemeanors. The maximum jail time for these offenses is one year, although a first DUI does not usually result in any jail time. The maximum fine amount for these offenses is $2,500. The driver will spend six months in jail if they had a child passenger in the car at the time of the DUI.

​Read More:​ When Is a DUI a Felony in Illinois?

For second offenses, the court may order five days in jail or 40 hours of community service, as well as the possibility of drug and alcohol counseling.

Third or subsequent DUIs are felonies with minimum jail time of 90 days and the possibility of years in prison. Fines are usually topped at $2,500, but can go up to $25,000 if a child passenger was present. The mandatory driver's license revocation period is 10 years for a third offense.

​Read More:​ Illinois DUI Records Guide: How to Remove DUIs From Your Record