20 C.F.R. § 1002.38
Yes. In certain occupations (for example, longshoreman, stagehand, construction worker), the employee may frequently work for many different employers. A hiring hall operated by a union or an employer association typically assigns the employee to the jobs. In these industries, it may not be unusual for the employee to work his or her entire career in a series of short-term job assignments. The definition of "employer" includes a person, institution, organization, or other entity to which the employer has delegated the performance of employment-related responsibilities. A hiring hall therefore is considered the employee's employer if the hiring and job assignment functions have been delegated by an employer to the hiring hall. As the employer, a hiring hall has reemployment responsibilities to its employees. USERRA's anti-discrimination and anti-retaliation provisions also apply to the hiring hall.
20 C.F.R. § 1002.38