The article discusses the key role that Section 10 of the Lanham Act played in the recent decision by the US Court of Appeals for the Federal Circuit in Emerald Cities Collaborative, Inc. v. Sheri Jean Roese. The Trademark Trial and Appeal Board ruled the assignment of the mark “The Emerald City” to the Emerald Cities Collaborative, Inc. constituted an improper assignment of an intent-to-use-based trademark application, and therefore ordered the cancellation of the registration that had issued for such mark. Following an appeal, the Federal Circuit affirmed this decision. The ruling serves as a critical reminder regarding the laws prohibiting the assignment of intent-to-use based on trademark applications, the risks in pursuing enforcement efforts when a mark might not have been properly assigned and the importance of asserting common law rights in a notice of opposition.