When an assignment has the effect of materially changing the duties that the obligor must perform, it is ineffective. Changing the party to whom the obligor must make a payment is not a material change of duty that will defeat an assignment, since that, of course, is the purpose behind most assignments. Nor will a minor change in the duties the obligor must perform defeat the assignment.
Several residents in the town of Centerville sign up on an annual basis with the Centerville Times to receive their morning paper. A customer who is moving out of town may assign his right to receive the paper to someone else within the delivery route. As long as the assignee pays for the paper, the assignment is effective; the only relationship the obligor has to the assignee is a routine delivery in exchange for payment. Obligors can consent in the original contract, however, to a subsequent assignment of duties. Here is a clause from the World Team Tennis League contract: “It is mutually agreed that the Club shall have the right to sell, assign, trade and transfer this contract to another Club in the League, and the Player agrees to accept and be bound by such sale, exchange, assignment or transfer and to faithfully perform and carry out his or her obligations under this contract as if it had been entered into by the Player and such other Club.” Consent is not necessary when the contract does not involve a personal relationship.