(a) No marine employer shall engage or employ any individual to serve as a crewmember unless the individual passes a chemical test for dangerous drugs for that employer.

(b) An employer may waive a pre-employment test required for a job applicant by paragraph (a) of this section if the individual provides satisfactory evidence that he or she has:

(1) Passed a chemical test for dangerous drugs, required by this part, within the previous six months with no subsequent positive drug tests during the remainder of the six-month period; or

(2) During the previous 185 days been subject to a random testing program required by § 16.230 for at least 60 days and did not fail or refuse to participate in a chemical test for dangerous drugs required by this part.