Petition for Rulemaking; Notification of Petition for Rulemaking; Invalid Specimen Determinations

This document announces receipt of a petition for rulemaking received by DOT on February 27, 2026, to initiate a rulemaking to amend 49 CFR part 40. The petitioner's proposed amendments seek to incorporate structured medical verification standards when an employee asserts a plausible medical explanation for abnormal specimen validity findings, including abnormal pH values. Specifically, the petitioner proposes: a defined and finite documentation submission window; required written Medical Review Officer determinations addressing submitted documentation; defined evaluation standards for abnormal urinary chemistry findings; consideration of specialist consultation when diagnosed voiding disorders are asserted; and (5) documented review of medically supported functional voiding disorders prior to verifying refusal determinations based on inability to provide a specimen under direct observation. Through this notification, DOT seeks comment on the petition, as well as any information that could be used in DOT's determination whether to grant the petition.