The Doctrine of Equivalents (DOE) has traditionally been justified as a way to overcome language limitations, mistake, and unforeseeability. Ironically, these elements are missing from leading DOE case law.
Michael Meurer and Craig Nard have released a working paper that brings to light a new justification for the DOE. According to Meurer and Nard, a highly skilled and motivated patent attorney / inventor team would not need the doctrine of equivalents. Through thoughtful and clever claim drafting, the team could obtain patents that would directly cover any potential infringers. This thoughtfulness and cleverness, however, will have a large price tag (i.e., many hours for a highly paid patent attorney).
We develop a better explanation of why claim breadth falls short of the maximum breadth allowed by patent law. Our explanation replaces the passive patent attorney depicted in the friction theory with an active inventor and attorney who are capable of responding effectively to the frictions mentioned above. Whether an inventor obtains the broadest permissible claim breadth depends mostly on the talent and effort of the inventor and attorney in identifying what has been enabled. A good attorney predicts the embodiments that could be chosen by infringers and finds appropriate language to draft a suitably broad claim. We call this process claim refinement, and we develop a refinement theory of the doctrine of equivalents.
Because the pricetag associated with patent drafting is so large, Meurer and Nard argue that such a cost will not be socially optimal. The DOE serves to accomodate less-than-perfect claim drafting — thus allowing a better allocation of resources.