Time to Revisit Exclusion of the Prosecution History in Patent Litigation

Abstract:

Canada, like many other countries, makes the entire prosecution history of a patent available to the public. Despite its existence as a certified public document, the patent prosecution history is inadmissible for the purposes of construing the claims of the patent or interpreting the scope of the patent monopoly when such issues arise in litigation. This judge-made rule is inconsistent with how legal documents are generally interpreted and out of step with how the rest of the world treats patent prosecution histories.



Canada’s exclusion of the prosecution history from consideration during patent construction is based on questionable doctrinal origins and detrimentally affects the public notice function of patents. The exclusionary doctrine has also insidiously harmed the traditional patent doctrines of obviousness and utility in Canadian law. An approach that allows the consideration of the prosecution history would improve the predictability of these doctrines and enhance the public notice and definitional functions of the patent. We suggest that the exclusionary rule perpetuated in Canadian law be relaxed and harmonized with the practices of other jurisdictions to ensure that patents reflect the bargain actually struck between the patentee and the public.