這算不算勞動剝削？美國有什麽樣的法律管這樣的事？

兩個 independent contractors　Ａ　and Ｂ 給政府部門服務，Ａ　billed US goverment for B's service. Between A and B, there is no any signed contract.　Meanwhile B is using A's office and personel.

B should get a credit for his service which was collected under A's name, right?

If A does not want to give B any credit, 算不算A剝削B's勞動?what can B do? What kind of labor law A violates? In what name should B sue A?