If this was a DOT drug test, a laboratory positive is not final until the Medical Review Officer (MRO) completes the verification process. As of October 14, 2026, the MRO interview is your chance to provide information relevant to the result, and you have 72 hours after notice of a verified positive or certain refusals to ask the MRO for split-specimen testing.
A split specimen means a second portion of the original urine sample was sealed at collection. It is not a new test or a new sample. The useful distinction is explained in this guide to MRO review: a lab finding starts the process, while the MRO verification is the DOT result that follows.
What will the MRO tell you in the interview?
As of October 14, 2026, 49 CFR 40.135 requires the MRO to tell you the laboratory reported a positive, adulterated, substituted, or invalid result, as applicable. The MRO must also identify the drug or drugs reported positive, or explain the basis for an adulterated or substituted finding.
The MRO must explain how the verification interview works and that the decision is based on information you provide in that interview. If more medical evaluation is needed, the MRO can ask you to complete it; failing to do so is treated as declining to discuss the result. The rule also requires a warning that certain result and safety-sensitive medical information may be disclosed to third parties without your consent.
There is no fixed MRO call time in the Part 40 provisions discussed here. If you receive an MRO message, respond promptly and have any relevant prescription or medical information ready. A verified result can sometimes be changed in the limited situations described in 49 CFR 40.149, including certain later information about a legitimate medical explanation or a laboratory error.
What the MRO cannot decide for you
As of October 14, 2026, 49 CFR 40.151 limits the MRO’s role. The MRO cannot use a drug test that was not collected or tested under Part 40 as part of verification. The MRO also does not decide disputes about what happened at the collection site when they are not reflected on the federal custody-and-control form, or whether your employer had grounds to order the test.
The MRO also cannot verify a DOT test as negative because a physician recommended a Schedule I drug under state law. The Department of Transportation says this includes medical marijuana: a state medical-marijuana recommendation is not a valid medical explanation for a DOT positive as of October 14, 2026. See the DOT’s medical marijuana notice for the agency’s wording.
That DOT rule is different from a general workplace policy or a state employment rule. For a non-DOT test, start with your employer’s written policy; this page on workplace drug-test policies explains why that document matters.
How do you request a split-specimen test?
As of October 14, 2026, once the MRO notifies you of a verified positive, or a refusal based on adulteration or substitution, 49 CFR Part 40 Subpart H gives you 72 hours from notification to request testing of the split specimen. You may make the request verbally or in writing to the MRO. There is no split-specimen test for an invalid result.
| Question | DOT answer as of October 14, 2026 |
|---|---|
| What is tested? | The sealed second portion of the original specimen. |
| When can you ask? | Within 72 hours after MRO notification of a verified positive or qualifying refusal. |
| How do you ask? | Tell the MRO verbally or in writing. |
| Where does it go? | The MRO directs the first laboratory to send it to a second HHS-certified laboratory. |
| What if it does not reconfirm? | The MRO must report the test as cancelled, subject to the specific Part 40 procedures. |
| Who makes it happen? | The employer must ensure timely testing; it cannot make testing wait for your direct payment or reimbursement agreement. |
If a serious injury, illness, lack of actual notice, inability to contact the MRO, or another unavoidable circumstance kept you from requesting within 72 hours, you can give the MRO documentation. If the MRO finds the reason legitimate, the rule requires the split test to proceed. The MRO must document the request’s date and time and promptly direct the first laboratory to forward the sealed split specimen.
For DOT testing, the split test checks whether a second HHS-certified laboratory reconfirms the finding from the same original specimen. If it reconfirms a positive, that positive is final under Part 40. If it fails to reconfirm all primary results, the MRO reports that the test must be cancelled under the applicable Part 40 procedure.
Before you act
- Check whether your test is DOT-regulated or governed by a non-DOT employer policy.
- Keep the MRO’s contact details and the time you received notice.
- If you want a DOT split-specimen test, make the request to the MRO within the 72-hour window.
- For a non-DOT result, ask HR for the written policy and its retest process.
This is general information, not legal advice. Deadlines can be short, so talk to HR, a union representative, or an employment lawyer quickly if you need advice about your own situation.
By HealthDataConsortium.org Research Team
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.
