Last reviewed Oct 26, 2026. General information, not legal advice.
A reasonable suspicion test happens when a supervisor sees signs that a driver may be impaired. It is one of the hardest calls a supervisor makes, so the rules ask for training and good notes.
What counts as reasonable suspicion
The decision must be based on what the supervisor sees, hears or smells right now. For example:
- Slurred speech or trouble walking
- The smell of alcohol or marijuana
- Unusual behavior that is out of character
Rumors, a tip or past behavior alone are not enough.
Supervisor training
Supervisors who make these calls for CDL drivers must be trained to spot signs of drug and alcohol use. Keep a record of each supervisor’s training.
Write it down
The supervisor should write down what they saw, when and where, and sign it. Do this quickly, while it is fresh.
What happens next
- Remove the driver from safety-sensitive work.
- Get the driver to a collection site. Don’t let them drive themselves.
- Do the drug test, alcohol test, or both, based on what was seen.
How we help
Our compliance management plans help you keep supervisor training records and testing paperwork in order.