The case is Geffner v. The Coca-Cola Company, issued on June 27. The claim is that calling it "diet" Coke is misleading because it does not promise weight-loss. The Second Circuit notes that it has issued two summary orders this year on this issue involving Dr. Pepper and Pepsi. It now puts this issue to rest in a published opinion.
The Court (Cabranes, Raggi and Droney) starts off by swiftly rejecting any claims that the use of attractive models for Diet Coke advertising is misleading. The Court note that this sort of propaganda is ubiquitous in the advertising world such that it cannot reasonable be understood to "convey any specific meaning at all." The Court adds that the statement that Diet Coke will "not go to your waist" is vague and non-specific and really amounts to inactionable puffery. In other words, the advertising campaign is loaded with the meaningless language and imagery intended to sell as much of this chemical shitstorm as possible.
Turning to the main event, calling it "diet" Coke is not misleading. That label refers to the drink's low caloric content, and "it does not convey a more general weight loss promise." At oral argument on this appeal, the plaintiffs' lawyer insisted that research proves that Diet Coke actually causes you to gain weight. That argument is not referenced in this opinion. Rather, the point here is that calling it a "diet" product is legal since it "connotes simply that the 'diet' version of the drink is lower in calories than the 'non-diet' version of the drink."