This document summarizes the historical background of exclusionary conduct in antitrust law. It discusses how courts have struggled for decades to distinguish lawful competitive conduct from unlawful anticompetitive behavior by monopolists. In the late 19th century, large trusts dominated many industries, inspiring the Sherman Act of 1890 which aimed to promote competition and prohibit monopolies. However, the precise definitions of "exclusionary" and "predatory" conduct remained elusive. One of the earliest significant cases was against Alcoa in 1945, where the court found the company unlawfully monopolized the aluminum ingot market through expanding production capacity in an intentional effort to exclude competitors. This Alcoa standard of monopolization became influential through the 1970s.