Alcohol, drugs and DUI: Illinois SOS written test practice
5 free practice questions on alcohol, drugs and DUI for the Illinois SOS written knowledge test, each with the correct answer and a short explanation. Study them here, then check yourself in the interactive quiz or the exam simulator.
1. For drivers 21 years of age and older, driving with a blood alcohol concentration (BAC) is considered illegal starting at:
0.05%
✓ 0.08%
0.10%
Any detectable amount
Why: 0.08% — the legal limit for drivers aged 21 and older.
2. Under Illinois' zero-tolerance law, what BAC standard applies to drivers under 21?
0.08% or higher, same as adult drivers
✓ Any detectable amount of alcohol can result in license suspension
0.05% or higher
There is no separate standard for drivers under 21
Why: Illinois' zero-tolerance law means a driver under 21 can have their license suspended for having any detectable amount of alcohol in their system, well below the 0.08% adult limit.
3. A commercial vehicle driver is considered to be intoxicated if their BAC is:
0.08%
✓ 0.04% and higher
0.02%
0.10%
Why: For commercial drivers, a stricter limit applies—0.04%.
4. What does Illinois' implied consent law mean for drivers?
Drivers may refuse any chemical test with no consequences
✓ By driving in Illinois, a driver has already agreed to submit to chemical testing if lawfully arrested for DUI
Only drivers over 21 are subject to implied consent
Chemical testing is optional and requires a warrant
Why: By operating a vehicle on Illinois roads, drivers automatically consent to chemical testing (breath, blood, or urine) if lawfully arrested for DUI; refusing triggers an automatic license suspension.
5. Drivers and passengers are prohibited from having the following items inside the vehicle:
Food or drinks
✓ An open container of alcohol
Phone Holder
Sunglasses
Why: Open containers of alcohol are prohibited inside the vehicle for both the driver and passengers.