Once the Cat is Out of the Bag – Taking Advantage of Grace Periods for Patent Application Filings

December 12, 2017
By Isi Caulder and Maria Wei

Note: an update to this article was published on July 29, 2020. Click here to read the article.

In order to receive valid patent protection, an invention must be novel and inventive. To assess whether a patent application meets these requirements, the patent office looks to the “prior art” in the public domain at the time the application was filed. Public disclosure of an invention prior to filing the application with the patent office can thwart patent protection for that invention.

Fortunately, several countries, including Canada, operate “grace periods” for applicants that have made public disclosure prior to filing. Patent offices in these countries will not consider disclosures made by the applicant or a person who obtained knowledge from the applicant during the grace period as prior art for novelty and inventive step.

How Can a Grace Period Help?

Grace periods can permit applicants to file after disclosing the invention. In some jurisdictions, grace periods are limited to specific disclosures such as displays at officially recognized exhibitions, presentations at officially recognized academic or technical meetings, publications by officially recognized journals, or experimental testing.

In addition, grace periods can also protect a patent application from indirect public disclosure. That is, public disclosure made by a third-party, through the applicant. For example, in Canada, public disclosure made by a third-party who obtained knowledge from the applicant is not considered to be prior art.[1] Unauthorized disclosure, in which public disclosure is made in breach of the applicant’s confidence, may also benefit from grace periods.

It is important to note that grace periods do not protect a patent application from independent, third-party disclosure. As such, grace periods should not be relied upon to postpone filing a patent application and obtaining a filing date.

Patent offices also have different requirements that must be met in order to benefit from grace periods. For example, applicants may be required to inform the patent office about the public disclosure at the time of filing the patent application. Applicants may also be required to furnish proof of the public disclosure within a prescribed time after filing.

Calculating Grace Periods

Grace periods are typically 6 months or 12 months in length. However, there are two different methods of calculating grace periods. The basic method is with the grace period ending on the date of filing a patent application with that national patent office.

Another method of calculating a grace period accounts for priority rights. Priority rights allow an applicant to file a subsequent application with a patent office and claim the filing date of a first application with a foreign patent office for the same invention. The subsequently filed application is said to “claim priority” to the first application.

The second method effectively allows applicants to stack the grace period and the period to claim priority. That is, the grace period ends on the date of filing the first application in any country from which priority is claimed, the “priority date”.

What About Canada’s Grace Period, ‘eh?

Canada currently operates a 12 month grace period for novelty and inventive step based on the Canadian filing date.[2] The Canadian grace period ends on the date of filing a Canadian patent application with the Canadian Intellectual Property Office (CIPO).

However, legislative amendments to the Patent Act, which are not yet in force, will change how the grace period is calculated in Canada.[3] The amendments will adopt the second method of calculating the grace period, extending the grace period to the priority date. At the time of this article, no date for coming into force has been established yet.

Where Else Can I File Once the Cat is Out of the Bag?

The World Intellectual Property Organization (WIPO) offers a handy summary of grace periods in most jurisdictions.[4] The following is a brief list of grace periods for select countries that may be particularly relevant to Canadian applicants. Again, the types of disclosure permitted under the grace period of each jurisdiction can vary.

  • United States and Brazil operate 12 month grace periods based on the priority date for novelty and inventive step.[5]
  • Argentina and Mexico operate 12 month grace periods based on the priority date for novelty only.[6]
  • Australia and Republic of Korea operate 12 month grace periods based on the filing date for novelty and inventive step.[7]
  • China, Germany, and the United Kingdom operate 6 month grace periods based on the filing date for novelty only. [8]
  • Japan operates a 6 month grace period based on the filing date for novelty only.[9]

Another Saving Grace

It may still be possible to obtain valid patent protection in countries without grace periods or where a grace period has been exceeded. An invention may still be novel and inventive if the information publicly disclosed does not enable a person of ordinary skill in the art to perform the invention without undue burden. The question of whether disclosure is enabling depends on the facts of each particular case.

The grace period of each jurisdiction is unique in what types of disclosure is permitted, when the grace period operates, and how the grace period is calculated. Despite best efforts to keep the cat in the bag before filing a patent application, life happens. Keep calm, and file where possible within the grace period.

[1] Patent Act, RSC 1985, c P-4, s. 28.2(1), 28.3.

[2] Ibid.

[3] Bill C-43, Economic Action Plan 2014 Act, No. 2, 2nd Sess, 41st Parl, 2014, ss. 123, 124.

[4] World Intellectual Property Organization, Certain Aspects of National/Regional Patent Laws (Status as of October 2017), online: <>.

[5] Ibid.

[6] Ibid.

[7] IP Australia, Grace Periods, online: <> and supra, note 4.

[8] Supra, note 4.

[9] Ibid.

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