49 CFR § 219.303 - Reasonable suspicion observations.
(a) With respect to an alcohol test, the required observations must be made by a responsible railroad supervisor (defined by § 219.5) trained in accordance with § 219.11(g). The supervisor who makes the determination that reasonable suspicion exists may not conduct the reasonable suspicion testing on that regulated employee.
(b) With respect to a drug test, the required observations must be made by two responsible railroad supervisors (defined by § 219.5), at least one of whom must be both on site and trained in accordance with § 219.11(g). If one of the supervisors is off site, the on-site supervisor must communicate with the off-site supervisor, as necessary, to provide him or her the information needed to make the required observation. This communication may be performed via telephone, but not via radio or any other form of electronic communication.
(c) This subpart does not authorize holding any employee out of service pending receipt of toxicological analysis for reasonable suspicion testing, nor does it restrict a railroad from taking such action based on the employee's underlying conduct, provided it is consistent with the railroad's policy and taken under the railroad's own authority.
(d) The railroad must maintain written documentation that specifically describes the observed signs and symptoms upon which the determination that reasonable suspicion exists is based. This documentation must be completed promptly by the trained supervisor.