The Doctrine of Intervening Rights Under U.S. Patent Law|
The doctrine of intervening rights under U.S. patent law is based on Section 252 of the Patent Act. This statute applies to reissued patents, and it states that anyone who made, purchased, offered to sell, or used within the United States, or imported into the United States, an invention that is covered by a reissued patent but was not covered by the original patent may continue to do so without liability for infringement. The doctrine of intervening rights is an equitable defense to patent infringement, and the purpose of the doctrine is to protect investments made in good faith based on the scope of a patent that is subsequently broadened.
U.S. patent practice provides for two types of reissued patents--broadening reissues and narrowing reissues. A broadening reissue is one that broadens the scope of the claims (and, therefore, the scope of the patent), and it must be brought within two years of the date of issuance of the patent. A narrowing reissue is one that narrows the scope of the claims, and it can be brought at any time during the term of the patent. In theory, a patent may be reissued only if the patent is deemed wholly or partly inoperative or invalid because of a defective specification or drawing or because the patent holder claimed more or less than he had a right to claim. In other words, there must be some error in the original patent that serves as a basis for the reissue.
In order to rely on the doctrine of intervening rights, the defendant in a patent infringement action must show that he relied in good faith on the scope of the original patent. If the defendant began selling the products at issue after issuance of the original patent, then an argument could be made that the
defendant waited for the patent to issue to determine the scope of the claims, determined that his product did not fall within the scope of the original patent, and then began selling the products in reliance on his (or his attorney's) interpretation of the original patent. If, however, the defendant began selling the products before the original patent issued, such conduct suggests that the decision to sell the products was not made in reliance on the scope of the original patent. Thus, there is a relatively small window in which the doctrine of intervening rights applies--between the date of issuance of the original patent and the date of issuance of the reissue patent.
The doctrine of intervening rights only applies in situations where the reissue patent is broader than the original patent. Although there have been some conflicting court decisions, in general, if the reissue narrows the scope of the patent, then the doctrine of intervening rights is not available to a potential infringer. This makes sense because the point of the intervening rights doctrine is to protect defendants from being "trapped" by a patent that is subsequently broadened to encompass their activities.
The intervening rights defense applies both to products and to processes. Neither the product nor the process needs to have been actually sold or practiced before the patent was reissued; it is sufficient for intervening rights to apply that the defendant made substantial preparations to manufacture the product or practice the process prior to reissue.
The doctrine of intervening rights is not the same as prior user rights. Prior user rights, as they exist under current law, apply only to business methods. We will address prior user rights in the next issue of Intellections.