No person shall be issued a document required for employment on a merchant vessel of the United States nor shall any person be employed on a merchant vessel of the United States unless the Commandant is satisfied that the character and habits of life of such person are such as to authorize the belief that the presence of the individual on board would not be inimical to the security of the United States: Provided, That the Commandant may designate categories of merchant vessels to which the foregoing shall not apply.
[E.O. 10352, 17 FR 4624, May 21, 1952]