The Department of Justice argued that, apart from what it characterized as attempts or intent to monopolize, Alcoa's mere possession of the power to control prices and curb competition was an illegal monopoly per se under both sections 1 and 2 of the Sherman Act.

It insists that it never excluded competitors; but we can think of no more effective exclusion than progressively to embrace each new opportunity as it opened, and to face every newcomer with new capacity already geared into a great organization, having the advantage of experience, trade connections and the elite of personnel.

But that acknowledgement has generally been seen as an empty one in the context of the rest of the opinion, because rivals in a market routinely plan to outdo one another, at the least by increasing efficiency and appealing more effectively to actual and potential customers.

[1] In 1947, Alcoa made the argument to the court that there were two effective new entrants into the aluminum market – Reynolds and Kaiser – as a result of demobilization after the war and the government's divestiture of defense plants.

In 1958 Harvey Machine Tools Company began primary aluminum production, marking the end of Alcoa's monopoly over the process which had led to its domination of the American market.

Future Federal Reserve chairman Alan Greenspan criticized United States v. Alcoa as a young man in 1966, in an essay published in Capitalism: The Unknown Ideal.

Whatever damage the antitrust laws may have done to our economy, whatever distortions of the structure of the nation's capital they may have created, these are less disastrous than the fact that the effective purpose, the hidden intent, and the actual practice of the antitrust laws in the United States have led to the condemnation of the productive and efficient members of our society because they are productive and efficient.