46 U.S.C. § 7503

A license, certificate of registry, or merchant mariner’s document authorized to be issued under this part may be denied to an individual who— (1) within 10 years before applying for the license, certificate, or document, has been convicted of violating a dangerous drug law of the United States or of a State; or (2) when applying, has ever been a user of, or addicted to, a dangerous drug unless the individual provides satisfactory proof that the individual is cured.