The Federal Trade Commission (FTC) v. Mary Carter Paint Co. case in 1965 revolved around an antitrust dispute where the FTC alleged that Mary Carter Paint Co., along with several other paint manufacturers, had engaged in a conspiracy to fix prices and divide markets for their products, which violated Section 5 of the Federal Trade Commission Act. The company defended itself by arguing that its unique marketing strategy was not illegal but rather competitive and beneficial to consumers. This strategy involved offering customers shares of company stock as part of their purchases, thereby incentivizing larger orders and customer loyalty while also increasing public ownership of the firm's equity. However, this approach raised concerns about potential anti-competitive effects since it could potentially discourage competition from smaller firms unable to offer similar incentives or lead to market concentration if large numbers of customers became shareholders. In its decision, the Supreme Court ruled against Mary Carter Paint Co., finding that such practices did indeed constitute unfair methods of competition under federal law due to their potential impact on market dynamics.

In the dissenting opinion for Federal Trade Commission v. Mary Carter Paint Co., Justice Harlan argued that the majority's decision to uphold FTC's cease and desist order was flawed due to its failure to consider whether or not there was a reasonable probability of future violations by Mary Carter Paint Co. He contended that it is essential for FTC, before issuing such an order, to demonstrate more than just past misconduct but also a likelihood of recurrence in the future. In this case, he believed that no such evidence had been presented; hence, he disagreed with the majority’s ruling. Furthermore, Justice Harlan criticized what he saw as an overly broad interpretation of Section 5(a)(6) of the Federal Trade Commission Act by his colleagues on bench which could potentially lead to abuse and overreach by regulatory agencies like FTC.