In the post-Civil War era, rapid technological development in the US fueled significant economic growth and catalyzed local businesses to expand into interstate trusts that wielded monopolistic power through active combinations. The Republican Party’s pro-business ideology aligned with academia’s advocacy for laissez-faire economic policies and the public’s preference for limited federal regulation, allowing Republicans to dominate Congress and the presidency throughout much of this period. Unchecked, unregulated monopolistic practices exacerbated economic inequalities and social injustices, ultimately sparking widespread public demand for federal antitrust legislation. Despite the Sherman Act of 1890, Republicans, including “trust-buster” Theodore Roosevelt, strategically weakened its enforcement through vague language, selective prosecution, and expanded executive power. By analyzing congressional records and drawing on historians’ treatises, this study reveals how Republicans shaped the Sherman Act to serve their interests, delaying its passage and undermining its effectiveness. The Clayton Act of 1914, under Democratic leadership, finally addressed these shortcomings by clarifying legal ambiguities and strengthening regulatory oversight. As AI drives another era of rapid technological change, this history underscores the critical need for proactive and robust government regulation to prevent the emergence of unchecked power and maintain a balanced system of governance.