Amendment Based Estoppel at PTAB?

Remember the Doctrine of Equivalents (DOE)?

DOE was that folksy doctrine that allowed some wiggle room in proving patent infringement where a claim term was not literally met.  That is, DOE allows a patent owner to reach an equivalent claim element functioning in the same way, to achieve the same result that is utilized to side-step the literal claim language.  DOE is the type of legal argument that litigators live for.  Unfortunately, the doctrine was all but laid to rest decades ago in the Supreme Court’s Festo decision as most prosecution changes will foreclose DOE.  Still, there is an occasional throwback case that attempts to litigate DOE.

Most recently, Columbia University faced a summary judgment motion arguing that its DOE-based assertion was precluded by amendment based estoppel — as a result of PTAB claim cancellation alone.
Continue Reading Cancelling Claims at the PTAB & The Doctrine of Equivalents