Cease and Desist Letter – Warning Letter

When a patentee finds his patent right being infringed by a third party, he may send an alleged infringer a cease and desist letter. It is to warn the infringer of legal responsibilities and demand the cessation of infringement activities. Furthermore, the accused infringer, at least from the day of receiving the warning letter, will not be able to deny his intent or negligence in the infringement activities.

This warning letter plays an important role in proving the claim of damage compensation as well as the criminal liability for infringement. For criminal action, it is required to prove the intent of an infringer regarding infringing acts of a patent without doubt. In particularly, infringer’s intent in the infringement shall not be presumed even if a patent marking is present on the patented product. With a warning letter, it is easy and convenient to prove the infringer’s intent beyond reasonable doubt. Therefore, a patentee has often sent warning letters to infringers to point out the ownership of the patent and their infringing activities.