Traffic Law and Traffic Crash Investigation
What this domain tests
This domain tests the Illinois Vehicle Code (625 ILCS 5), impaired driving enforcement, crash reporting duties, and roadside investigation procedure.
Core rules
- A traffic stop requires reasonable suspicion of a violation.
- DUI under 625 ILCS 5/11-501 requires driving or actual physical control of a vehicle on a highway while under the influence, or with a BAC of 0.08 or more. Commercial drivers are at 0.04. Drivers under 21 fall under zero tolerance.
- Implied consent (625 ILCS 5/11-501.1): the officer reads the statutory warning. First refusal means a 12-month summary suspension; a second refusal means 3 years. A first failure at 0.08 or more means a 6-month suspension; a second means 1 year.
- Breath testing in Illinois requires a 20-minute observation period before the sample.
- Crash duties: 625 ILCS 5/11-401 requires stopping and reporting when a crash causes injury or death; 11-406 requires a written report when damage exceeds $1,500; 11-408 covers the investigating officer's report. 11-501.6 requires chemical testing when a crash causes death or personal injury.
- Scott's Law (625 ILCS 5/11-907(c)): when approaching a stationary emergency vehicle with lights on, change lanes if possible or reduce speed and proceed with caution.
Worked example
A driver rear-ends a car at a light. Officers smell alcohol, observe slurred speech and poor balance, and administer standard field sobriety tests. The driver refuses testing. The officer reads the implied consent warning, documents the refusal, and serves the summary suspension notice. Because no warrant is obtained and no test occurs, the refusal itself drives the suspension.
Traps
Treating the crash report as a fault determination - it is a factual record, not an adjudication. Administering a breath test without the 20-minute observation. Reading the implied consent warning after the test instead of before. Failing to document the driving or physical control element in a DUI.