FROM 1890 until 1972 it was easy for courts to compute damages in antitrust cases. Once the plaintiff showed the "fact" of injury, the court would indulge all reasonable inferences in that party's favor when computing the "quantum" of injury. All loss proximately caused by the violation would be found, trebled, and awarded to the plaintiff, with attorneys' fees as a bonus. All this seemed natural. After all, the statute says that "[a]ny person who shall be injured in his business or property by reason of anything forbidden in the antitrust laws ... shall recover three-fold the damages by him sustained, and the cost of suit, including a reasonable attorney's fee." Yet in other parts of the law courts routinely decline to equate plaintiffs' actual losses with the amount recoverable as damages. They use the specification of damages to achieve substantive goals. For example, in the law of contracts the courts rarely award the injured party full consequential damages. If the person who contracted for a machine loses profits while delays in delivery idle the rest of his plant, that is too bad. The plaintiff in such a case recovers only the difference between the agreed-on price and the actual cost of obtaining a similar item from another supplier. The rules of damages in contract law as a group serve important functions in creating incentives to prepare for transactions, make, and breach contracts when it is optimal to do so; damages supplement inevitably incomplete contracts.2 In 1972 the Supreme Court began to fit antitrust damages to substantive ends. It held that Hawaii could not recover for diminished taxes and injury to its economy caused by what it assumed to be a cartel of oil