5 C.F.R. § 339.301 : Administrative Personnel — OFFICE OF PERSONNEL MANAGEMENT — CIVIL SERVICE REGULATIONS — MEDICAL QUALIFICATION DETERMINATIONS — MEDICAL EXAMINATIONS — Authority to require an examination

(a) A routine pre-employment medical examination is appropriate only for a position with specific medical standards and/or physical requirements, or that is covered by a medical evaluation program established under this part.
(b) Subject to §339.103, an agency may require an applicant or employee who has applied for or occupies a position that has medical standards and/or physical requirements, or is covered by a medical evaluation program established under this part, to report for a medical examination:
(1) Subsequent to a tentative offer of employment or reemployment (including return to work from medically based absence on the basis of a medical condition);
(2) On a regularly recurring, periodic basis after appointment in accordance with §339.205; or
(3) Whenever the agency has a reasonable belief, based on objective evidence, that there is a question about an employee's continued capacity to meet the medical standards or physical requirements of a position.
(c) An agency may require an employee who has applied for or is receiving continuation of pay or compensation as a result of an injury or disease covered under the provisions of the Federal Employees' Compensation Act to report for an examination to determine medical limitations that may affect job placement decisions.
(d) An agency may require an employee who is released from his or her competitive level in a reduction in force under part 351 of this chapter to undergo a relevant medical evaluation if the position to which the employee has assignment rights has medical standards and/or physical requirements, that are different from those required in the employee's current position.
(e)
(1) An agency may order a psychiatric examination (including a psychological assessment) only when:
(i) The result of a current general medical examination that the agency has the authority to order under this section indicates no physical explanation for behavior or actions that may affect the safe and efficient performance of the applicant or employee, the safety of others, and/or the vulnerability of business operation and information systems to potential threats, or
(ii) A psychiatric examination or psychological assessment is part of the medical standards for a position having medical standards or required under a medical evaluation program established under this part.
(2) A psychiatric examination or psychological assessment authorized under paragraphs (e)(1) of this section must be conducted in accordance with accepted professional standards by a licensed physician certified in psychiatry by the American Board of Psychiatry and Neurology or the American Osteopathic Board of Psychiatry and Neurology, or by a licensed psychologist or clinical neuropsychologist, and may only be used to make inquiry into a person's mental fitness as it directly relates to successfully performing the duties of the position without significant risk to the applicant or employee or others, and/or to the vulnerability of business operation and information systems to potential threats.

5 C.F.R. § 339.301

82 FR 5350, 1/18/2017