A valid priority claim can allow a patent application to benefit from the filing date of an earlier patent application so as to exclude certain prior art from consideration. The recent decision of the U.S. Federal Circuit in Yeda Research and Development Co v Abbott GmbH & Co is a reminder of the importance of ensuring the validity of priority claims so that the associated benefits can be attained. Indeed, a valid priority claim is similarly important when filing in Canada, making it important to understand both the similarities and the differences between Canada and the U.S., when it comes to making a priority claim.

Yeda Research

At issue in Yeda Research was the citability of a novelty-destroying reference. The case turned on whether the patent at issue was entitled to the benefit of a priority claim to an earlier application antedating that reference.

Under U.S. law, in order for the claims of a patent to benefit from the filing date of an earlier application, various requirements must be satisfied. Amongst these, the claimed invention must have been disclosed by the earlier application in a way that clearly allows a person of ordinary skill to recognize that the inventor had invented what is claimed and possessed the claimed subject matter as of the date of filing of the earlier application.

The Court in Yeda Research was faced with deciding whether the disclosure in the earlier application was sufficient to satisfy this written description requirement having regard to the claimed invention in the patent at issue. The Court held that it did because the claimed subject matter had been inherently disclosed in the earlier application.

Disclosure Requirements for Priority Claims in Canada

Canada’s Patent Act allows a Canadian application to claim priority to an earlier filed foreign application if, amongst other things, the earlier application upon which the priority claim is based is an “application for a patent disclosing the subject-matter defined by the claim” of the Canadian application.

Consistent with Yeda Research, in Canada, disclosure in a priority document need not be explicit. Instead, decisions of Canada’s Federal Court suggest that even in the absence of an explicit disclosure, subject matter being relied upon for the priority claim may merely “be inferable from the language of the priority document”.

Effect of a Priority Claim in Canada

Where an application benefits from a valid priority claim, third-party disclosures may be compared to an earlier date than the application’s filing date when assessing their citability for anticipation or obviousness.

In particular, as in the U.S., this pivotal date is assessed on a claim-by-claim basis and, in Canada, is referred to as the “claim date” of each claim. Absent a valid priority claim, the claim date of every claim in an application is simply the application’s Canadian filing date—that is, either the date the application was filed in Canada or, in the case of a national phase entry of a PCT application, the international filing date. However, if priority is claimed, a claim will take the filing date of the earliest priority document disclosing the subject-matter defined by that claim as its claim date.

Notably, however, the claim date is only applicable to third-party disclosures. While a one-year grace period for inventor-derived disclosures exists, the grace period extends back from the Canadian filing date, not the claim date.

Requesting Priority in Canada

Classes of documents to which priority may be claimed in Canada are quite broad and generally similar to those available in the U.S.

For example, Canada’s Patent Act allows a priority claim to any application filed by the applicant in Canada or any country that is a World Trade Organization (WTO) member or that belongs to the Paris Convention. Canada also allows priority claims to applications filed with the European Patent Office (EPO), PCT applications and applications submitted to intergovernmental authorities such as, for example, the African Regional Intellectual Property Organization (ARIPO).

The Canadian Patent Office also recognizes Paris Convention priority based on foreign utility models and petty patents.

Finally, akin to the U.S., so-called “domestic” priority claims may also be made to an earlier filed Canadian application.

However, in contrast to U.S. practice, a Canadian patent application may not claim priority to a design patent, an industrial design application, or the like.

When a priority claim may be made

Under Canada’s Patent Rules, a request for priority to an earlier application can be made on or after filing. No government fee is required for claiming priority in either case.

In order for a request for priority to be timely, the request must be made and the Canadian Patent Office generally must be informed of particulars of the priority applications—filing date, country of filing and application number—within sixteen months of the filing date of the earliest priority application.

In any event, for an applicant to be entitled to priority from an earlier filed application, the filing date of the Canadian application claiming priority must be within twelve months of the filing date of the earlier application.

Notably, the interaction of these two time periods means that a decision about priority need not be made at filing as the applicant will always have at least four months before all priority claims must have been requested.

Restoration of priority to become part of Canadian law

Canada does not currently allow restoration of the right of priority in the case of late filings. However, this may soon change: upon the coming-into-force of recent amendments to Canada’s Patent Act, the aforementioned twelve month time limit in which the Canadian application must have been filed in order to have a valid priority claim will, in certain cases of unintentional failure to timely file a Canadian application claiming priority, be extendable by two months. That said, the exact contours of these provisions, including whether or not they will apply to domestic priority claims, remain unclear as regulations to support the new statutory provisions are not yet available.

No Requirement for certified copies

Unlike in the U.S., in Canada, certified copies of priority applications are usually not required even in the case of claims for foreign priority. Instead, the Canadian Patent Office’s practice is to attempt to retrieve the priority application from what it deems reliable sources such as, for example, PATENTSCOPE or from the International Bureau. If, however, examiners cannot retrieve the priority application or they have questions as to its accuracy, they may requisition a certified copy.

Concluding Remarks

All told, while the requirements for claiming priority in Canada and the U.S. are similar, there are important differences, particularly regarding formalities, that may affect filing strategy and the citability of prior art.