This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
Assignment of a contract is the transfer by one of the parties thereto to another person not a party thereto of his interest therein. "Assignment" is properly used only of non-negotiable instruments.1 In discussing the nature and effect of assignment it must be distinguished from novation. If A and B have entered into a contract with each other, and B, without A's consent, transfers his interest in such contract to C, the transaction is an assignment. But if A, B and C enter into a contract whereby B's rights and liabilities are transferred to C in whole or in part, and A releases B from the liabilities thus transferred to C, a new contract is formed and the prior contract is abandoned. This transaction is a novation. An assignment must also be distinguished from a sub-contract. In an assignment by B to C, all B's rights assigned to C pass to C, leaving C to assert such rights against A, B having no interest therein. In a sub-contract B retains all his rights against A, but B makes a contract with C to aid B in performing his contract with A. Such sub-contract does not in the absence of statute give C any rights against A, nor has C any contractual relations with A. A distinction must also be made between a total assignment of all one's rights under a contract and an assignment of a part only of such rights. Assignment by act of the parties, that is by contract, must also be distinguished from the so-called assignment by operation of law. The latter is the title by which contract rights are acquired without the act or consent of their former owner, as by an executor or administrator in a decedent's estate, by a trustee in bankruptcy in a bankrupt's estate, by a husband in his wife's property at Common Law and the like.
1 Townsend v. Carpenter, 11 Ohio 21.