The “rule of reason” remains after almost forty years the most curious obiter dictum ever indulged in by the Supreme Court of the United States. Mistaken though it was in its basic assumptions, the rule nevertheless persists as the Court's standard for construing the Sherman Act. This is not to say, as some critics have said, that the rule has seriously hampered the Department of Justice in enforcing the antitrust laws. We have it on the authority of Thurman Arnold that without the rule die Sherman Act would be “unworkable … because every combination between two men in business is in some measure a restraint of trade.” The rule, he has said, “has the effect of preventing the antitrust laws from destroying the efficiency of diose combinations that are actually serving, instead of exploiting, the consumer.” The fact remains, however, that in adopting the rule the Court erred in at least two respects: first, in applying a test of reasonableness where in the early cases at least none was called for and, second, in basing that rule on a misunderstanding of the common law. For the first of its sins the Court has been scolded many times; for the second, it has received surprisingly litde criticism.
