In the United States v. American Sugar Refining Company case of 1905, the U.S Supreme Court ruled on a significant antitrust matter. The American Sugar Refining Company had acquired several sugar refining companies and controlled about 98% of all sugar refining in the United States. The government argued that this constituted a monopoly and violated the Sherman Antitrust Act, which prohibits business activities that federal government regulators deem to be anti-competitive. However, in its decision, the court held that manufacturing was not considered interstate commerce and thus could not be regulated by Congress under its Commerce Clause powers. Therefore, it concluded that even though American Sugar's acquisition might have created a monopoly within an individual state or even nationally across many states' markets for refined sugar production (a manufacturing process), such monopolization did not violate federal law because it didn't directly involve trade between states - i.e., interstate commerce - which is what federal antitrust laws were designed to regulate.

The dissenting opinion in the United States v. American Sugar Refining Company case argued that the majority's interpretation of the Sherman Antitrust Act was too broad and could potentially stifle legitimate business practices. The dissenters believed that not all monopolies were inherently harmful or illegal, especially if they resulted from superior skill, foresight, or industry rather than anti-competitive behavior. They contended that a monopoly should only be deemed unlawful under the Act if it involved an unreasonable restraint on trade or commerce among several states. In this particular case, they did not see sufficient evidence to prove such a violation by American Sugar Refining Company. Furthermore, they expressed concerns about potential negative impacts on economic growth and innovation due to overzealous application of antitrust laws.