Medical Review Officer (MRO) Expert Witness

A Medical Review Officer (MRO) expert witness is a licensed physician who is specially trained to interpret and verify drug and alcohol testing results in accordance with established testing standards. The Medical Review Officer serves as an independent clinical gatekeeper between the laboratory and the employer or requesting entity by evaluating confirmed laboratory results and determining whether a legitimate medical explanation exists, such as a valid prescription or documented medical condition. The MRO role is most commonly associated with regulated testing programs, including Department of Transportation (DOT) testing, as well as workplace drug testing and other fitness-for-duty contexts.

Medical Review Officers are physicians who complete specialized MRO training and demonstrate competence in drug testing procedures, laboratory result interpretation, pharmacology basics relevant to testing, chain-of-custody principles, and the process required for lawful and defensible verification. MROs do not function as treating physicians in this role. Their task is to review results objectively, conduct required donor interviews, request and evaluate supporting documentation when indicated, and make verification determinations under applicable program rules.

Role of the Medical Review Officer Expert Witness

In litigation, Medical Review Officer expert witnesses evaluate whether drug testing results were handled, reviewed, verified, and reported in compliance with applicable standards. This may include analysis of laboratory confirmation methods, chain of custody, specimen validity testing, documentation requests, donor interview process, verification determinations, and reporting timelines.

MRO experts are also asked to clarify what an MRO is and is not responsible for. The MRO does not manage employer policy decisions or employment actions. Instead, the MRO’s responsibility is to determine whether a confirmed result should be verified as positive, negative, canceled, or otherwise reportable under the governing rules, and whether a legitimate medical explanation exists.

Key Issues in Medical Review Officer Litigation

Disputes commonly involve alleged failures to follow required verification steps, misinterpretation of laboratory results, inadequate donor interview documentation, improper acceptance or rejection of prescription explanations, and deviations from mandated procedures regarding refusal to test, shy bladder, adulteration, substitution, dilution, or invalid results. Cases may also raise questions about use of legally prescribed medications, medication-assisted treatment, cannabinoids, opioids, stimulants, benzodiazepines, and other drug classes frequently encountered in workplace and regulated testing programs.

In regulated matters, MRO-related disputes may also involve whether determinations were consistent with program requirements, whether required re-testing or split specimen procedures were properly handled, and whether reported outcomes were medically and procedurally defensible.