Patent Publication Dates

Once a patent is granted, it can be asserted in litigation against an alleged infringer. One of the remedies that can be obtained is “reasonable compensation” for pre-grant infringement pursuant to section 55(2) of the Patent Act. While relief is often sought and granted for pre-grant infringement, the remedy has some subtleties, including those arising from changing practices at the Canadian Patent Office.

Section 55(2) of the Patent Act states the following:

55(2) A person is liable to pay reasonable compensation to a patentee and to all persons claiming under the patentee for any damage sustained by the patentee or by any of those persons by reason of any act on the part of that person, after the specification contained in the application for the patent became open to public inspection, in English or French, under section 10 and before the grant of the patent, that would have constituted an infringement of the patent if the patent had been granted on the day the specification became open to public inspection, in English or French, under that section.

The start date for liability for “reasonable compensation” is when the “specification contained in the application” became “open to public inspection” under Section 10 of the Patent Act. This date is presumably used because a third party first has the ability to review a pending application and assess their potential liability once it has been made available for inspection.

Section 10 of the Patent Act says that all patent applications “shall be open to public inspection”, subject to some limitations. The most important limitation is that an application shall not be open to public inspection earlier than 18 months after the priority date (or filing date if there is no claim for priority). This 18 month secrecy period is standard in most patent jurisdictions.

Patent applications that enter national phase in Canada from a PCT application are considered to have been opened for public inspection on the date the PCT application was published in English or French – see Section 157 of the Patent Rules. Since the national entry deadline is 30 months from the priority date, the national entry date for the vast majority of such applications is well after the PCT application was published.

However, the Canadian Patent Office does not have a statutory obligation to publish patent applications immediately upon the expiry of the 18 month secrecy period, only an obligation to keep pre-publication patent applications secret pursuant to Section 10 of the Patent Act and Section 16 of the Patent Rules and to make patent applications open to public inspection. This is in contrast to the Patent Cooperation Treaty (PCT) which requires publication after 18 months to be “effected promptly”.

In the past, the Canadian Patent Office published a weekly “Canadian Patent Office Record” that contained various statutorily required information (such as the list of locations that could receive physical mail required in section 5(4) of the old Patent Rules) but also patent applications newly published under Section 10 of the Patent Act. The Canadian Patent Office Record was discontinued in 2024 as part of the Canadian Patent Office’s Next Generation Patent (NGP) project.

Currently, newly published patent applications are simply added to the Canadian Patent Database and can be located using the usual search tools, including using the “Open to Public Inspection Date” field.

Because of delays in the processing of some patent applications, some patent applications have not been added to the public patent database until well after the 18 month period. As a result, the date it was open for public inspection printed on the patent cover sheet is not 18 months after the priority date but in some cases is a significantly later date. The longest located is over two and a half years after the filing date for publication of a patent application.

Because there is no longer a Canadian Patent Office Record, it can be difficult to precisely determine when a particular patent application was first made available in the patent database and therefore actually first available to be found by a search. In situations where the exact date a particular patent application was first made available in Canada is important, further investigation with the Canadian Patent Office may be required. This is particularly the case for patent applications published in the last several years.