 If, in a basic example, Warne sells a car to Cullinan, and Cullinan has not the money to pay for it, Warne may refuse to hand over the car.In contracts of mandate, similarly, to a real-estate agent claiming commission before the sale of a house, one may deploy the "exceptio" to refute her claim for specific performance.Where the innocent party receives and starts using part-performance or defective performance, the contract cannot then be cancelled, as an election to keep the contract alive has been made, but the innocent party may raise the "exceptio".