The federal anti assignment statutes do not apply to an assignment that arises by operation of law. However, the anti assignment statutes apply to assignments that arise due to the voluntary acts of the parties. For instance, the transfer of a claim for accrued rent to a transferee of property under lease to the United States is exempt from application of the federal anti assignment statutes.
A claim for patent infringement by the United States does not come under the purview of the voluntary assignment prohibition of the federal anti assignment statutes.[i] Numerous classes of assignments are judicially exempted from the operation of Assignment of Claims Act. The largest category of excised assignments is those which, in one form or another, occur by operation of law. Various such assignments, which are regularly held to be unaffected by the Act, include the passage of claims to heirs and devisees, transfers made incident to proceedings in bankruptcy or receivership, transfers by the succession of one business entity for another, assignments made by judicial sale or order, and assignments produced by operation of the law of subrogation.
[i] Rel-Reeves, Inc. v. United States, 221 Ct. Cl. 263 (Ct. Cl. 1979)