What Are the 2-Hour and 8-Hour Time Limits for FMCSA Reasonable Suspicion Alcohol Tests?

FMCSA reasonable suspicion testing under 49 CFR 382.307 depends on timing. The rule sets two clock points, 2 hours and 8 hours, measured from the moment a trained supervisor decides a test is needed. The wider process, including what counts as reasonable suspicion, is covered in the requirements for a reasonable suspicion test.

The decision that starts the clock. A carrier requires a reasonable suspicion alcohol test only when it has reasonable suspicion that the driver violated the alcohol prohibitions. That suspicion rests on specific, contemporaneous, articulable observations about the driver's appearance, behavior, speech or body odors, made by a supervisor or company official trained under 49 CFR 382.603 (49 CFR 382.307(a) and (c)). For alcohol, the observations are made during, just before, or just after the period of the workday when the driver must comply with the alcohol rules (49 CFR 382.307(d)). The person who makes the determination may not conduct the alcohol test.

The 2-hour mark. If the alcohol test is not given within 2 hours after the determination, the carrier prepares and keeps on file a record stating the reasons the test was not promptly given (49 CFR 382.307(e)(1)).

The 8-hour mark. If the test is not given within 8 hours, the carrier stops attempting to give it and prepares and keeps a record stating why the test was not given (49 CFR 382.307(e)(1)).

Keeping the driver off duty. Even without a test, a driver may not report for duty or remain on duty in safety-sensitive functions while under the influence of or impaired by alcohol, as shown by behavioral, speech and performance indicators of alcohol misuse. The carrier may not permit it until an alcohol test shows a concentration below 0.02 or until 24 hours have passed since the determination (49 CFR 382.307(e)(2)). Apart from that, the carrier takes no action under Part 382 against the driver based only on behavior and appearance when no test was given.

Written record of observations. The supervisor who made the observations signs a written record of them within 24 hours of the observed behavior or before the results of the test are released, whichever is earlier (49 CFR 382.307(f)). Reasonable suspicion documentation is often the first thing reviewed in an audit.

Testing logistics. Meeting the 2-hour mark usually depends on having a breath alcohol technician or screening test technician available on short notice. The test steps are covered in how DOT breath alcohol screening and confirmation tests work. Section 382.307 sets no 8-hour cutoff for a reasonable suspicion drug test, though prompt collection is the practical goal.