Why a negative result is not a mistake
The standard in §382.307 is reasonable suspicion, built on specific, contemporaneous, articulable observations of appearance, behavior, speech, or body odors. It is not probable cause, and it is not certainty. A driver who is slurring, unsteady, and sweating at the start of a shift might be impaired, or might be sick, exhausted, grieving, or on a new prescription. The signs are the same. The test is how the employer tells them apart. 49 CFR 382.307(a)–(b)
That is also why waiting for certainty is the actual error. Once a trained supervisor has the observations, the rule says the employer shall require the test. A supervisor who declines to act until sure puts an impaired driver on the road some of the time and an unimpaired driver on the road the rest of the time, with no record either way. A supervisor who observes, writes it down, and tests gets a clean answer every time, and a negative answer is a clean answer. 49 CFR 382.603
What happens to the driver
After the result comes back
- Alcohol test below 0.02
- 49 CFR 382.307(e)(2)
- The hold ends. The driver may return to safety-sensitive functions as soon as the result is in hand; the 24-hour alternative applies only when no test reads below 0.02.
- Alcohol 0.02 to 0.039
- 49 CFR 382.505
- Not a violation, and not a negative either. The driver stays off safety-sensitive functions until the next regularly scheduled duty period and not less than 24 hours after the test. The employer may take no other action under Part 382 on that result.
- Controlled substances result negative
- 49 CFR 382.601(c)
- Part 382 sets no federal hold while the laboratory and MRO work. Many employers keep the driver off safety-sensitive duty until the MRO reports; that is a company rule under independent authority, and the written policy should label it as one.
- Discipline
- 49 CFR 382.307(e)(3)49 CFR 382.505(b)
- None under Part 382. With no test, the employer may not act under the rule on behavior and appearance alone; with a test, it may not act on an alcohol result under 0.04. Anything beyond that comes from the company’s own authority, if the policy says so plainly.
Results that are not actually negative
Four outcomes get called “negative” in the yard and are not. Each has its own next step, and in two of them the next step belongs to the employer, not the laboratory.
| Result | What it is | What happens next | Rule |
|---|---|---|---|
| Negative dilute | A negative result on a urine specimen the laboratory found dilute. | Creatinine 2 to 5 mg/dL: the MRO directs an immediate recollection under direct observation. Above 5 mg/dL: the employer may direct one more test, with minimal notice, applied the same way to everyone in that test type. The second result is the result of record. | 49 CFR 40.197 |
| Cancelled | A test with a problem that cannot be or has not been corrected. Neither positive nor negative. | Depends on the reason. For an invalid result that requires it, direct a new collection under direct observation immediately, with no advance notice and no other consequence. | 49 CFR 40.349 CFR 40.23(f) |
| Insufficient specimen | The driver could not produce 45 mL of urine or 2 mL of oral fluid within the allowed time. | The collector notifies the DER. After consulting the MRO, the DER sends the driver for a physician evaluation within five days. A medical condition cancels the test; no medical basis makes it a refusal. | 49 CFR 40.193 |
| Refusal at the site | Leaving before the collection is complete, declining to attempt a second specimen, or other conduct listed in Part 40. | The collector reports the conduct to the DER and the employer decides whether it is a refusal. A refusal is a violation, not a negative. | 49 CFR 40.191(d)(1) |
Is the result actually negative?
Did the MRO report the controlled substances result as negative, rather than negative dilute, cancelled, or invalid?
Yes: Continue to question 2.
No: Use the table above. A dilute or invalid result may require another collection, and a cancelled test is neither positive nor negative.
Did the alcohol test read below 0.02, or was no alcohol test required because the observations pointed only to drug use?
Yes: Continue to question 3.
No: A result of 0.02 to 0.039 keeps the driver off safety-sensitive functions until the next regularly scheduled duty period and at least 24 hours. A result of 0.04 or greater is a violation.
Is the supervisor’s written observation record signed and in the file?
Yes: The driver returns to safety-sensitive functions. Keep the record with the result for at least two years.
What stays on file
A negative result generates almost as much paper as a positive one. None of it goes to the Clearinghouse, which receives violations only. 49 CFR 382.705
Records to keep after a negative result
- The signed observation record
- 49 CFR 382.307(f)
- Required regardless of the result. Signed within 24 hours of the behavior or before the results came back, whichever was earlier. Do not revise it after the result.
- Documents behind the decision to test
- 49 CFR 382.401(c)(1)(v)49 CFR 382.401(b)(2)
- The observation record, notes, timing, and any reason an alcohol test was late or never given. Collection-process records: keep at least two years.
- The negative result itself
- 49 CFR 382.401(b)(3)
- Negative and cancelled controlled substances results and alcohol results under 0.02: keep at least one year.
- Any medical explanation
- 49 CFR 382.401(c)(1)(vii)
- Documents verifying a medical explanation for a driver’s inability to provide an adequate breath, urine, or oral fluid specimen.
Related guides
- Reasonable suspicion checklist and observation form: the signs, the clocks, and a free two-page form.
- What is reasonable suspicion drug and alcohol testing: the whole process, start to finish.
- When a driver refuses a reasonable suspicion test: what counts as a refusal and what the employer must do next.
- Who does what in a reasonable suspicion test: supervisor, DER, collector, MRO, and SAP.
Frequently asked questions
Does a negative result mean the supervisor was wrong to order the test?
No. 49 CFR 382.307 requires the test when a trained supervisor has reasonable suspicion based on specific, contemporaneous, articulable observations. It does not require certainty, and it does not grade the supervisor on the outcome. Fatigue, illness, medication, and distress can all produce the same signs as impairment, and the test is how the employer finds out which it was. The supervisor who observed, documented, and tested did exactly what the rule asks.
Can the driver be disciplined after a negative reasonable suspicion test?
Not under Part 382. The rule bars the employer from taking action under Part 382 against a driver based solely on behavior and appearance with respect to alcohol when there is no test, and from acting on an alcohol result below 0.04. An employer with independent authority may apply its own rules, but a policy that does so must say clearly that the rule rests on the company’s own authority rather than on the federal regulation.
Does the driver go back to work right away?
For alcohol, the hold ends as soon as a test reads below 0.02; the alternative is 24 hours after the determination. For controlled substances, Part 382 sets no federal hold while the laboratory and MRO work; most employers keep the driver off safety-sensitive duty until the MRO reports, which is a company rule under independent authority and should be written and labeled as one.
What is a negative dilute result?
A negative result on a urine specimen the laboratory found to be dilute. If the creatinine level is between 2 and 5 mg/dL, the MRO directs an immediate recollection under direct observation. Above 5 mg/dL, the employer may, but need not, direct one more test, with the least possible notice, and must apply the same choice to every employee in the same type of test. The second result becomes the result of record.
What if the driver could not provide enough urine?
The collector gives the driver up to three hours and up to 40 ounces of fluid for a urine test, or up to one hour for oral fluid. If no sufficient specimen is produced, the collector notifies the DER, who, after consulting the MRO, directs the driver to a physician evaluation within five days. If a medical condition explains it, the test is cancelled. If not, the MRO records a refusal to test. Unsupported claims of anxiety or dehydration do not count as a medical condition.
Is a cancelled test a negative test?
No. Part 40 defines a cancelled test as one with a problem that cannot be or has not been corrected, and says it is neither positive nor negative. Depending on the reason, the employer may have to collect again. For an invalid result that requires it, the employer must immediately direct a new collection under direct observation and may attach no other consequence to the invalid finding.
Does a negative reasonable suspicion test go to the Clearinghouse?
No. Employers and MROs report violations: verified positive, adulterated, or substituted results, alcohol results of 0.04 or greater, refusals, and the return-to-duty milestones. A negative reasonable suspicion result, and the supervisor’s observation record behind it, stay in the employer’s own files under 49 CFR 382.401.
Sources
Every citation on this page was checked against the eCFR text current as of October 30, 2026.
- 49 CFR 382.307 — Reasonable suspicion testing
- 49 CFR 382.505 — Other alcohol-related conduct (0.02 to 0.039)
- 49 CFR 382.401 — Retention of records
- 49 CFR 382.601 — Employer policy; independent authority provisions
- 49 CFR 382.603 — Training for supervisors
- 49 CFR 382.705 — Reporting to the Clearinghouse
- 49 CFR 40.3 — Definitions (negative result, cancelled test)
- 49 CFR 40.23 — Employer actions after verified results
- 49 CFR 40.191 — What is a refusal to take a DOT drug test
- 49 CFR 40.193 — Insufficient amount of specimen
- 49 CFR 40.197 — Dilute urine specimens
