49 CFR § 199.103 - Use of persons who fail or refuse a drug test.
(1) Fails a drug test required by this part and the medical review officer makes a determination under DOT Procedures; or
(2) Refuses to take a drug test required by this part.
(b) Paragraph (a)(1) of this section does not apply to a person who has -
(1) Passed a drug test under DOT Procedures;
(2) Been considered by the medical review officer in accordance with DOT Procedures and been determined by a substance abuse professional to have successfully completed required education or treatment; and
(3) Not failed a drug test required by this part after returning to duty.
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