In this installment of the “Content Matters” column, Jenner & Block Partner Andrew J. “A.J.” Thomas and Associate L. David Russell explore the doctrine of “aesthetic functionality,” first invoked in 1952 by the Ninth Circuit to deny trademark protection. Since then, the doctrine’s vitality has waxed and waned; it was considered “practically dead” by the early 2000s, then revived in the Ninth Circuit’s 2011 decision in Fleischer Studios v. A.V.E.L.A. The authors review other recent decisions, in the Sixth and Second Circuits, and observe that “aesthetic functionality inquiries force courts to draw difficult distinctions – asking whether a design is favored by consumers because it suggests an affiliation with a source or simply because it is visually pleasing. This is especially true when the design is a cartoon character or other entertainment image.” Ultimately, they conclude that an expansive aesthetic functionality doctrine poses a significant threat to entertainment brands because the popularity of such marks derives from precisely the reputational strength and goodwill that trademark law is designed to protect.