The United States v. Terminal Railroad Association of St. Louis case in 1914 revolved around the issue of monopoly and restraint of trade, specifically regarding railroad terminal facilities in St. Louis, Missouri. The Supreme Court ruled that the Terminal Railroad Association's control over all access to rail transportation into and out of St. Louis constituted a violation of the Sherman Antitrust Act because it restrained interstate commerce by limiting competition among railroads for traffic through this key hub city. The court ordered that other railway companies should be allowed reasonable and non-discriminatory access to these essential facilities under fair conditions supervised by a federal district court-appointed board or trustee system, thereby ensuring competitive equality among carriers using those terminals.

In the dissenting opinion for United States v. Terminal Railroad Association of St. Louis, it was argued that the majority's decision to deem the Terminal Railroad Association as a monopoly and thus in violation of the Sherman Antitrust Act was incorrect. The dissenting justices believed that this case did not involve interstate commerce but rather local traffic within St. Louis, which should be outside federal jurisdiction under states' rights principles. They also contended that there wasn't sufficient evidence to prove an intent or effect to restrain trade or create a monopoly on part of the association; instead, they saw its actions as legitimate business practices aimed at efficiency and convenience for all railroads using their facilities - something beneficial for public interest rather than harmful competition-wise.