Doctrine of Intervening Rights Law and Legal Definition

Doctrine of Intervening Rights is invoked to determine the validity of patent reissues whose claims are broader than those outlined in the original patent. It is the right of a person who practiced a patent's broadened claims to continue practicing, even though a patent is later reissued with broader claims because of inadvertent claim errors in the original patent.

The patent laws protect those who in good faith relied on the scope of the patent as originally issued in making, using, or selling some invention or process. They are said to have acquired intervening rights. If such use of the invention or process was not covered by the patent as originally issued, the statute protects that use. In such cases the court must find that there is no infringement on the basis of the absolute intervening rights. Even if a person or business has not used the invention but has made substantial preparation towards making, using or selling it prior to the patent's reissue, equitable intervening rights may still be found. [35 USCS § 252]