The physical and mental examination of arriving aliens (including alien crewmen) shall be made by medical officers of the United States Public Health Service, who shall conduct all medical examinations and shall certify, for the information of the immigration officers and the immigration judges, any physical and mental defect or disease observed by such medical officers in any such alien. If medical officers of the United States Public Health Service are not available, civil surgeons of not less than four years’ professional experience may be employed for such service upon such terms as may be prescribed by the Attorney General. Aliens (including alien crewmen) arriving at ports of the United States shall be examined by at least one such medical officer or civil surgeon under such administrative regulations as the Attorney General may prescribe, and under medical regulations prepared by the Secretary of Health and Human Services. Medical officers of the United States Public Health Service who have had special training in the diagnosis of insanity and mental defects shall be detailed for duty or employed at such ports of entry as the Attorney General may designate, and such medical officers shall be provided with suitable facilities for the detention and examination of all arriving aliens who it is suspected may be inadmissible under paragraph (1) of section
1182
(a) of this title, and the services of interpreters shall be provided for such examination. Any alien certified under paragraph (1) of section
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(a) of this title, may appeal to a board of medical officers of the United States Public Health Service, which shall be convened by the Secretary of Health and Human Services, and any such alien may introduce before such board one expert medical witness at his own cost and expense.