Cease and desist is an official warning to stop any activity deemed unlawful or unauthorized. This ultimatum is typically issued through a formal letter, informing the recipient that if they do not discontinue the specified activity they may be subject to legal action. Cease and desist letters are used in many scenarios including copyright infringement, trademark violations, patent disputes, slander, and more. In other words, when someone tells you to “cease and desist,” they’re telling you to stop what you’re doing right now – because it could have serious consequences.