Since the coming-into-force date of new section 53.1 of the Patent Act in December 2018, Canadian practitioners have been waiting to see how broad this “file wrapper estoppel” provision will be interpreted. Recently, the Federal Court released a decision that expands the scope of s. 53.1 to potentially include foreign prosecution file wrappers. However, this case is currently under appeal.
Section 53.1(1) states that written communications prepared in respect of the prosecution of a patent application between the applicant or patentee and an employee of the Canadian Patent Office may be admitted into evidence to rebut any representation made by the patentee in claim construction. However, the Court held in Canmar Foods Ltd. V TA Foods LTD (2019 FC 1233) that foreign prosecution could be admissible to the court under “extraordinary circumstances”.
During the prosecution of Canadian Patent No. 2,582,376, a Response to an Office Action stated “New claims 1 to 19 correspond substantially to those submitted during prosecution of a related United States application” and “the newly submitted claims are much narrower in scope than the previously examined claims”. Accordingly, the Court held that because the patentee specifically referenced the corresponding US Application’s prosecution history and acknowledged that the amendments were made to overcome novelty and obviousness concerns raised in the US Application’s prosecution history, the applicable US Application’s prosecution history was admissible. The Court stated that if they were to ignore the US prosecution history in this specific case, “patent applicants in Canada would be incentivized to intentionally refrain from being transparent with the Canadian Patent Office as to why amendments were made to limit claims during prosecution”. However, an unintended consequence of this case may be that patent practitioners may intentionally refrain from being transparent. Instead of providing Examiners with information regarding where the amendments are coming from, Applicants are now incentivized to not mention any reference to foreign prosecution. Under this interpretation, Applicants would be better served to merely state that the claim amendments are not disclosed, taught or fairly suggested by the prior art without reference to a foreign Patent Office’s work.
The Court held that “extraordinary circumstances” arise where “the patentee acknowledges that the claims have been amended to be substantially the same as claims submitted in another jurisdiction, and the patentee admits that the amendments have limited the scope of claims in order to make the claims novel and non-obvious”. When this occurs, the Court held that the foreign prosecution history is admissible for the limited purpose of purposively construing the Canadian claims. The Court specifically mentioned expedited examination via the Patent Prosecution Highway (PPH), where Applicants are required to identify allowable claims in another jurisdiction and amend the claims to substantially conform to those allowable claims. Accordingly, Canmar appears to suggest that the foreign prosecution history of the Office of Earlier Examination (i.e., the country with allowable claims to which a PPH request is being made) will be admissible in court as there is an implicit admission that the amendments limit the scope of the claims to be novel and non-obvious.
What does this mean for Canadian patent prosecution moving forward?
Canadian practitioners are well aware that anything put on the record in Canada may be admissible in US court proceedings. Accordingly, verbose Responses have always been avoided, and indeed directly referring to US prosecution was a way to avoid adding anything new to the worldwide file wrapper for that patent family. However, practitioners should avoid mentioning foreign prosecution history, even to show the Examiner that these amendments have been deemed allowable elsewhere. Furthermore, Applicants should be wary of entering PPH in Canada, as the prosecution history of the Office of Earlier Examination may be used to rebut a representation made by the patentee in claim construction.