[Footnote 1: _Standard Oil Co. v. United States_, 221 U.S., 1.

_United States v. American Tobacco Co._, id., 106.]

The Sherman Act[1] declares unlawful every contract, combination, or
conspiracy in restraint of interstate trade, and every attempt to
monopolize interstate trade. The legal uncertainties that have arisen in
its enforcement have not been with respect to the meaning of the terms
"restraint of trade" and "monopoly," although the popular impression is
to the contrary. In 1890, when the statute was passed, contracts in
restraint of trade and monopolies were already unlawful at common law,
and these terms, by a long series of decisions both here and in England,
had been defined as definitely as the nature of the subject matter
permitted. While incapable (like the term "fraud") of precise definition
covering all forms which the ingenuity of man might devise, nevertheless
their meaning and scope were well within the understanding of any man of
reasonable intelligence. Whatever legal uncertainties have arisen have
been chiefly owing to two questions: first, What is _interstate_ trade
within the meaning of the act? and second, Did the act enlarge the
common-law rule as to what restraints were unlawful?

[Footnote 1: "An Act to protect trade and commerce against unlawful
restraints and monopolies," approved July 2, 1890.]

The act was nearly shipwrecked at the outset on the first of these
questions. In the famous Knight case,[1] the first case under the
Sherman Act to reach the Supreme Court, it was held that the
transactions by which the American Sugar Refining Company obtained
control of the Philadelphia refineries and secured a virtual monopoly
could not be reached under the act because they bore no direct relation