Who among the listed roles is NOT involved in medical evaluations related to fitness for duty?

The role of Human Resources is typically involved in overseeing employee relations, policy enforcement, and compliance with employment laws, but it does not directly conduct medical evaluations related to fitness for duty. In a fitness-for-duty assessment process, medical evaluations are usually carried out by trained medical professionals who have the qualifications to assess an individual's health status in relation to their job responsibilities.

The FFD staff, Medical Review Officers, and Substance Abuse Experts are all directly connected to the evaluation process. FFD staff usually facilitate the assessment procedures, while Medical Review Officers specifically interpret medical evaluations and assess employee fitness in the context of substance use. Substance Abuse Experts provide specialized knowledge regarding the implications of substance use on job performance.

Thus, the Human Resources department plays a supporting and administrative role rather than a direct role in medical evaluations, making it the correct choice for the answer.