(a) The alcohol and/or drug testing authority conferred by this subpart does not apply with respect to any event that meets the criteria for post-accident toxicological testing required under subpart C of this part.

(b) This subpart does not authorize holding an employee out of service pending receipt of toxicological analysis for reasonable cause testing because meeting the testing criteria is only a basis to inquire whether alcohol or drugs may have played a role in the accident or rule violation. However, this subpart does not restrict a railroad from holding an employee out of service based on the employee's underlying conduct, so long as it is consistent with the railroad's policy and the action is taken under the railroad's own authority.

(c) When determining whether reasonable cause testing is justified, a railroad must consider the involvement of each crewmember in the qualifying event, not the involvement of the crew as a whole.