Starting with the 1945 Alcoa case, however, the Supreme Court ruled that size per se was an offense, irrespective of illegal acts. The fact that Alcoa had achieved 90 percent control of the aluminum market by efficient operation and by maintaining low profit margins was no defense. In the 1982 IBM and AT&T cases (see case Study 12-4), however, the Court took an intermediate position in its interpretation of Section 2 of the Sherman Act. While the Court backed away from the ruling that size per se was illegal, it ruled that size, together with practices that by themselves or when used by smaller firms did not represent an offense, were illegal when used by a very large firm. Thus, the Court ordercd AT&T to divest itself of 22 local telephone companies under a consent decree but decided to drop it
S case against IBM. Overall, Section 2 of the Sherman Act may have been more effective in preventing monopolization than in breaking.