这算不算劳动剥削？美国有什么样的法律管这样的事？

两个 independent contractors　Ａ　and Ｂ 给政府部门服务，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剥削B's劳动?what can B do? What kind of labor law A violates? In what name should B sue A?