5 U.S.C. § 6324

(a) Sick leave may not be charged to the account of a member of the Metropolitan Police force or the Fire Department of the District of Columbia, the United States Park Police force, or the United States Secret Service Uniformed Division for an absence due to injury or illness resulting from the performance of duty. (b) The determination of whether an injury or illness resulted from the performance of duty shall be made under regulations prescribed by— (1) the District of Columbia Council for members of the Metropolitan Police force and the Fire Department of the District of Columbia; (2) the Secretary of the Interior for the United States Park Police force; and (3) the Secretary of Homeland Security for the United States Secret Service Uniformed Division. (c) This section shall not apply to members of the United States Secret Service Uniformed Division who are covered under chapter 84 for the purpose of retirement benefits.