Efficient Breach - Posner's Illustration

Posner's Illustration

Judge Richard Posner gave this well-known illustration of efficient breach in "Economic Analysis of Law":

Suppose I sign a contract to deliver 100,000 custom-ground widgets at $.10 apiece to A, for use in his boiler factory. After I have delivered 10,000, B comes to me, explains that he desperately needs 25,000 custom-ground widgets at once since otherwise he will be forced to close his pianola factory at great cost, and offers me $.15 apiece for 25,000 widgets. I sell him the widgets and as a result do not complete timely delivery to A, who sustains $1000 in damages from my breach. Having obtained an additional profit of $1250 on the sale to B, I am better off even after reimbursing A for his loss. Society is also better off. Since B was willing to pay me $.15 per widget, it must mean that each widget was worth at least $.15 to him. But it was worth only $.14 to A – $.10, what he paid, plus $.04 ($1000 divided by 25,000), his expected profit. Thus the breach resulted in a transfer of the 25,000 widgets from a lower valued to a higher valued use.