The United States Supreme Court case, UNITED STATES v. AMERICAN LIVESTOCK COMMISSION COMPANY et al., 1928, revolved around the interpretation of the Packers and Stockyards Act of 1921. The American Livestock Commission Company was accused by the government of violating this act through their business practices which involved buying livestock on behalf of packers without disclosing to sellers that they were acting as agents for these packers. The court had to determine whether such actions constituted "unfair" or "deceptive" practices under the law. In a unanimous decision, it ruled in favor of the government stating that these undisclosed agency relationships could indeed be considered deceptive and unfair within meaning of statute because they potentially allowed for manipulation in pricing and competition among buyers.

The dissenting opinion in the case of United States v. American Livestock Commission Company et al., 1928, argued that the Sherman Act was not applicable to this situation as it did not involve interstate commerce. The justices contended that livestock sales were a local activity and thus outside federal jurisdiction under the Commerce Clause. They also disagreed with the majority's interpretation of what constituted an unlawful restraint on trade, arguing that there was no evidence presented showing any intent or effect to monopolize or restrain competition within the industry. Furthermore, they believed that applying antitrust laws in this context could have unintended consequences for other industries where similar practices are common and accepted as part of doing business.