How to Invent and Protect Your Invention: A Guide to Patents for Scientists and Engineers

7.6 PRIOR COMMERCIAL USE RIGHTS

One exception to the rule that the use of a patented product, process, or composition of matter constitutes infringement is prior commercial use rights. Prior commercial use occurs when a person or company makes, uses, or sells an invention and an unaffiliated inventor tries to patent the same invention. Under U.S. law, prior commercial use is a defense to infringement if the user used the invention either for an internal commercial purpose or for sale at least one year before the inventor disclosed the invention or filed for a patent. This may occur when a company is secretly making a product or using a process (to maintain it as a trade secret), and another person independently invents and patents the undisclosed product or process. Prior commercial use is almost always secret, because public uses of the invention would constitute prior art and destroy patentability.

7.6.1 Personal Defenses

Prior commercial use is a personal defense to infringement. Defenses protect the person that uses the defense from being sued for infringement. The defense does not mean that infringement did not occur; it simply means that the infringer had an acceptable excuse that prevents him from being held liable. A prior commercial user has a right to continue using the invention, even though such a use would ordinarily be infringement. For example, Goodyear has been using a particular process for fabricating tires for many years and kept the process a trade secret. Bridgestone ...