DOT Seeks Comment on Petition to Change Invalid Specimen Determinations

The Department of Transportation (DOT), through its Office of the Secretary, published a notification of a petition for rulemaking on invalid specimen determinations under 49 CFR Part 40 in the Federal Register on October 1, 2026. The notice is Federal Register document 2026-20169 (91 FR 62409), docket DOT-OST-2026-3664. DOT will accept comments, data and information on the petition until Monday, November 2, 2026.

This is not a proposed rule. DOT is asking for public comment on a petition for rulemaking it received on February 27, 2026, as well as any information that could help DOT decide whether to grant the petition. The current Part 40 requirements remain in effect.

The full notice is available on the Federal Register at Petition for Rulemaking; Notification of Petition for Rulemaking; Invalid Specimen Determinations.

What the Petition Asks For

DOT refers to the petition as the Darcy Kern Petition. The notice was signed on September 29, 2026 by Douglas Simon, Director of the Office of Drug and Alcohol Policy and Compliance (ODAPC).

The petitioner asks DOT to amend Part 40 to add structured medical verification standards when an employee asserts a plausible medical explanation for abnormal specimen validity findings, including abnormal pH values. According to the petition, Part 40 currently requires that certain invalid results, including pH values outside established physiological parameters, lead to cancellation of the test and a mandatory directly observed recollection, without a structured opportunity to document a medical explanation.

The petition proposes five changes:

1. A defined and finite window for submitting medical documentation.
2. Written Medical Review Officer (MRO) determinations addressing the submitted documentation.
3. Defined evaluation standards for abnormal urinary chemistry findings.
4. Consideration of specialist consultation when a diagnosed voiding disorder is asserted.
5. Documented review of medically supported functional voiding disorders before an MRO verifies a refusal based on an inability to provide a specimen under direct observation.

The Petitioner's Proposed Regulatory Text

The petitioner frames the changes as additions to 49 CFR 40.193, the section on what happens when an employee does not provide a sufficient amount of specimen. A footnote in the notice states that 49 CFR 40.159, which covers what the MRO does when a drug test result is invalid, seems to be the appropriate provision to be considered for amendment.

• Proposed 40.193(f), medical verification window. When an employee asserts a plausible medical explanation for abnormal validity findings, the MRO would give the employee a period of no more than 72 hours to submit documentation from a licensed medical provider. The MRO would issue a written determination on that documentation before directing a directly observed recollection under 49 CFR 40.67. If documentation is not submitted in time, or is found insufficient, the observed recollection would proceed under existing requirements.
• Proposed 40.193(g), specialist consultation. When the asserted explanation involves a diagnosed urological condition or functional voiding disorder, including psychogenic urinary retention (paruresis), the MRO would consider consulting a licensed urologist or licensed mental health professional before issuing a final determination.
• Pre-refusal documentation review. Before verifying a refusal to test based on failure to provide a sufficient specimen under direct observation, the MRO would document consideration of any previously submitted medical documentation of a functional voiding disorder.

The petitioner states that the changes would not weaken anti-adulteration safeguards, eliminate observed testing or create open-ended delays, and that laboratory validity thresholds would remain unchanged. The petition cites the consequences of refusal determinations, including potential commercial driver's license disqualification, Clearinghouse reporting and return-to-duty processes. These are the petitioner's statements; DOT has not taken a position on the petition.

What Happens Next

DOT will review the comments and information it receives to determine whether to grant the petition. The notice itself does not amend Part 40. The petition asks DOT to initiate rulemaking proceedings to evaluate and adopt the proposed amendments. Unless and until Part 40 is amended, MROs, employers, collectors and service agents continue to follow the current invalid result and observed collection procedures in Part 40.

How to Submit Comments

Comments are accepted until Monday, November 2, 2026, by one of the following methods:

• Online: the Federal eRulemaking Portal at regulations.gov, docket DOT-OST-2026-3664.
• Mail: Dockets Operations, U.S. Department of Transportation, 1200 New Jersey Ave. SE, West Building, W58-213, Washington, DC 20590-0001.
• Hand delivery: West Building, W58-213, 1200 New Jersey Ave. SE, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

DOT asks commenters to use only one method and to include the agency name, "Department of Transportation," and docket number DOT-OST-2026-3664 at the beginning of their comments. All comments are posted without change to regulations.gov, including any personal information provided, and comments submitted there cannot be claimed as confidential business information.