29 C.F.R. § 500.71
The Act prohibits any person from utilizing the services of a farm labor contractor to supply migrant or seasonal agricultural workers without first taking reasonable steps to determine that the farm labor contractor possesses a valid Certificate of Registration, issued pursuant to the Act, which authorizes the activity for which the contractor is to be utilized. This prohibition also applies to a farm labor contractor who wishes to utilize the services of another farm labor contractor (see § 500.41 ). In making the determination about a contractor's registration status, a person may rely upon the contractor's possession of a Certificate of Registration which on its face is valid and which authorizes the activity for which the contractor is utilized. A person has the alternative to confirm the contractor's registration through the central registry maintained by the United States Department of Labor.
29 C.F.R. §500.71