A cease and desist letter is a document sent to an individual or business to stop allegedly illegal activity. The phrase "cease and desist" is a legal doublet, made up of two near-synonyms. The letter may warn that, if the recipient does not discontinue specified conduct, or take certain actions, by deadlines set in the letter, that party, i.e. the letter's recipient, may be sued. When issued by a public authority, a cease and desist letter, being "a warning of impending judicial enforcement", is most appropriately called a "cease and desist order".
Although cease and desist letters are not exclusively used in the area of intellectual property, particularly in regards to copyright infringement, such letters "are frequently utilized in disputes concerning intellectual property and represent an important feature of the intellectual property law landscape". The holder of an intellectual property right such as a copyrighted work, a trademark, or a patent, may send the cease and desist letter to inform a third party "of the right holders' rights, identity, and intentions to enforce the rights". The letter may merely contain a licensing offer or may be an explicit threat of a lawsuit. A cease and desist letter often triggers licensing negotiations, and is a frequent first step towards litigation.
Receiving numerous cease and desist letters may be very costly for the recipient. Each claim in the letters must be evaluated, and it should be decided whether to respond to the letters, "whether or not to obtain an attorney's opinion letter, prepare for a lawsuit, and perhaps initiate [in case of letters regarding a potential patent infringement] a search for alternatives and the development of design-around technologies".
Cease and desist letters are sometimes used to intimidate recipients and can be "an effective tool used by corporations to chill the critical speech of gripe sites operators". A company owning a trademark may send such letter to a gripe site operator alleging a trademark infringement, although the actual use of the trademark by the gripe site operator may fall under a fair use exception (in compliance with, in the U.S., the protection of free speech under the First Amendment).
In 2017, a cease and desist letter sent by Netflix was noted by news outlets such as Fortune and Quartz for its humorous wording.
The Philippine National Telecommunications Commission issued a cease and desist letter ordering ABS-CBN to stop broadcasting on May 5, 2020, after its franchise expiry the day before (May 4, 2020). At 7:45 in the evening, ABS-CBN stopped its terrestrial broadcast. In compliance with the government order, ABS-CBN signed-off all of its radio stations and free television channels (Channel 2, DZMM, and MOR). The NTC gave ABS-CBN 10 days to explain why its assigned frequencies should not be recalled. On June 30, 2020, considering that Channel 43 was also included in the May 5, 2020 cease and desist letter issued by the NTC against ABS-CBN (although ABS-CBN CEO Carlo Katigbak insisted that it is part of their blocktime agreement with Amcara Broadcasting Network), the NTC and Solicitor General Jose Calida released two alias shutdown orders against Channel 43 on digital receiver ABS-CBN TV Plus and Sky Cable's nationwide satellite service Sky Direct.
Donald Trump also sent a cease and desist letter to CNN asking them to retract a poll that showed him being 14 percentage points behind his opponent Joe Biden during the presidential election, prompting The Atlantic to warn about such attacks on the media.
In 2021, Google's platform YouTube issued a significant number of cease and desist notices to the creators of various music bots on Discord. Some of the most notable bots to be sent this notice were Rythm and Groovy, at the time, the two most popular bots on the platform. These music bots allowed users to request songs and have the bot create a queue. This was done by pulling the audio stream from various streaming and video platforms, including YouTube, and then played that audio on the Discord voice channel. Unlike on the YouTube website, such music bots did not play any advertisements from YouTube, resulting in missing revenue for YouTube and the content uploaders. A spokesperson for Google told The Verge that Groovy violated YouTube's terms of service for "modifying the service and using it for commercial purposes". The makers of Groovy had decided to comply with Google's request by shutting down the bot on August 30, 2021. According to estimations, the bot had more than 250 million users.