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Illinois driving lesson · DUI & Drug Laws

Alcohol, cannabis and other drugs

A 3-minute lesson from the Illinois course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.

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Read time
3 minutes
Course unit
DUI & Drug Laws
Checkpoint questions
6
Source pages
51, 52

Alcohol is the number one killer on American roadways. It affects your vision and slows your reaction time, even below the legal limit. Cannabis and many ordinary medicines can impair you too. Illinois sets hard limits for each.

Blood-alcohol concentration (BAC)

A measurement of the amount of alcohol in your system, based on a test of your breath, blood, urine or other bodily substance.

Handbook p. 51 ↗
.08%

It is illegal to drive with a BAC at or above this level

Handbook p. 51 ↗

Know the rule

You can be convicted of DUI with a BAC below .08% if your driving ability is impaired.

Handbook p. 51 ↗

Your reaction to alcohol is also affected by:

  • The food you have recently eaten
  • Your tolerance of alcohol
  • Any drugs you have taken
Handbook p. 51 ↗

Know the rule

Only time removes the effects of alcohol. Food, coffee and showers do not speed up its elimination from your body.

Handbook p. 51 ↗

Illegal THC (cannabis) levels for driving

Illegal THC (cannabis) levels for driving
Tested substanceIllegal at
Whole blood5 nanograms or more per milliliter
Other bodily substance10 nanograms or more per milliliter
Handbook p. 51 ↗

Know the rule

It is illegal to drive with any trace of a controlled drug, substance or intoxicating compound in your blood.

Handbook p. 51 ↗

Know the rule

Illinois allows medical and recreational cannabis use for persons 21 and older. Medical users enroll in a program run by the Illinois Department of Public Health, and a notation goes on their driving record. No one may drive while impaired by cannabis.

Handbook p. 51 ↗

Cannabis and your vehicle:

  • Transport it only in a sealed, odor-proof, child-resistant container
  • No driver or passenger may use cannabis in a motor vehicle
  • If an officer suspects cannabis impairment, you must submit to field sobriety and/or roadside chemical tests
  • Refusing or failing those tests results in a license suspension
Handbook p. 51 ↗

Know the rule

Driving impaired by cannabis or transporting it illegally may cost you your driving privileges. A medical cannabis card holder may also have the card revoked for two years.

Handbook p. 51 ↗

Other drugs that can impair driving include:

  • Antihistamines and cold remedies
  • Pain relievers
  • Mood-changing drugs
  • Hashish, LSD, heroin, cocaine and morphine
  • Amphetamines and methamphetamines
Handbook p. 52 ↗

Know the rule

Mixing even small amounts of alcohol with other drugs is very dangerous.

Handbook p. 52 ↗

Put it into practice

After two drinks, your friend says a strong coffee and a cold shower will sober him up enough to drive. It won't. Only time removes alcohol from the body.

Check your understanding

Read the question, decide on an answer, then open it to check the explanation. These are Roadwise study questions based on the source handbook.

What is the illegal BAC for drivers age 21 and older in Illinois?
  1. 0.06%
  2. 0.08%
  3. 0.05%
  4. 0.10%

Answer: 0.08%

Illinois' legal BAC limit for adult drivers is 0.08%.

Handbook p. 51 ↗
Can a driver be convicted of DUI with a BAC below 0.08%?
  1. Yes, but only for commercial drivers
  2. No, only drug impairment counts below 0.08%
  3. Yes, if their driving ability is shown to be impaired
  4. No, 0.08% is an absolute floor for any DUI charge

Answer: Yes, if their driving ability is shown to be impaired

A DUI conviction is possible below 0.08% if impairment is shown.

Handbook p. 51 ↗
What illegal THC level applies to driving in Illinois, measured in whole blood?
  1. 2 nanograms or more per milliliter
  2. 10 nanograms or more per milliliter
  3. 1 nanogram or more per milliliter
  4. 5 nanograms or more per milliliter

Answer: 5 nanograms or more per milliliter

Illinois sets 5 ng/mL of whole blood (or 10 ng/mL of other bodily substance) as the illegal THC level.

Handbook p. 51 ↗
What speeds up the elimination of alcohol from your body, according to the handbook?
  1. Drinking coffee
  2. Only time
  3. Eating a large meal
  4. Taking a cold shower

Answer: Only time

Only time removes alcohol from your system, not food, coffee, or showers.

Handbook p. 51 ↗
How must cannabis be transported in a vehicle to remain legal?
  1. In the trunk in its original packaging only
  2. In a sealed, odor-proof, child-resistant container
  3. Anywhere in the vehicle if the driver is 21 or older
  4. In the glove compartment, unsealed

Answer: In a sealed, odor-proof, child-resistant container

Cannabis must be sealed, odor-proof, and in a child-resistant container.

Handbook p. 51 ↗
Besides alcohol and cannabis, which category of substances does the handbook warn can impair safe driving?
  1. Only illegal street drugs
  2. Prescription and over-the-counter drugs
  3. Only prescription drugs
  4. Only drugs taken with alcohol

Answer: Prescription and over-the-counter drugs

The handbook lists antihistamines, pain relievers, and other drugs as impairing.

Handbook p. 52 ↗
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