In the case of Federal Trade Commission v. Mandel Brothers, Inc., the Supreme Court ruled in favor of the Federal Trade Commission (FTC). The FTC had issued a cease and desist order against Mandel Brothers, a retail fur company, for violating Section 5 of the Federal Trade Act by misrepresenting their products' composition through false advertising and deceptive labeling practices. The court held that even if customers were not directly harmed or deceived by these practices, they still constituted unfair competition because they could potentially deceive or confuse consumers about what they were buying. Therefore, it was within FTC's power to regulate such conduct under its mandate to prevent business practices that are likely to cause consumer confusion or deception. This decision reinforced FTC's authority over businesses engaging in misleading marketing tactics.

In the dissenting opinion for Federal Trade Commission v. Mandel Brothers, Inc., Justice Whittaker disagreed with the majority's interpretation of Section 2(c) of the Clayton Act. He argued that this section was intended to prohibit brokerage payments only in those situations where they were used as a means of passing on discriminatory price reductions or rebates. In his view, there was no evidence presented in this case to suggest that such discrimination had occurred. Furthermore, he contended that interpreting Section 2(c) so broadly as to ban all brokerage fees paid by sellers would have far-reaching and potentially harmful effects on legitimate business practices and could even lead to increased prices for consumers due to reduced competition among brokers.