42 U.S.C. § 1654

This chapter shall not apply in respect to the injury or death of (1) an employee subject to the provisions of subchapter I of chapter 81 of title 5; (2) an employee engaged in agriculture, domestic service, or any employment that is casual and not in the usual course of the trade, business, or profession of the employer; and (3) a master or member of a crew of any vessel.