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Invention disclosure and patent grace periods: How disclosing your invention before filing a patent application can severely limit your ability to obtain a patent

One of the requirements for obtaining a valid patent is for your invention to be novel. This novelty requirement can differ between countries. In many countries, public disclosure of the invention by any person, including the patent applicant, before filing a patent application destroys novelty and the ability to obtain a valid patent. These countries are said to operate an “absolute novelty” requirement. Public disclosures can include written or electronic publications, public oral disclosures, public demonstrations, public use, offers for sale, and actual sales.

Other countries operate a “relative novelty” requirement that provide a grace period after public disclosure within which to file a patent application. A grace period is a prescribed time period after any public disclosure by the patent applicant or through the patent applicant within which a patent application may be filed without the disclosure being considered novelty destroying against the patent application. Immunity is granted to the patent applicant. The grace period generally does not protect against independent disclosures made by third parties prior to the filing date. Relative novelty countries that operate a twelve month grace period are listed in Table 1.

Relative novelty countries, including Canada and the United States, typically operate grace periods that extend back from the date the patent application is filed in the relevant country. However, in some relative novelty countries, such as Argentina, grace periods are particularly generous and extend back from the date the priority patent application was filed. The United States will also adopt a grace period extending back from the date the priority patent application is filed, for all applications with a priority date of March 16, 2013 or later.

Most relative novelty countries operate a ‘first-to-file’ system and the grace period typically acts to protect against inadvertent disclosures made by the applicant or through the applicant, and not disclosures made by independent third parties. The United States will continue to operate a ‘first-to-invent’ system until 16 March 2013, under which independent third party disclosures within the grace period may be excluded if it can be shown that the applicant invented the invention before the third party. From 16 March 2013 onwards, the United States will operate under the ‘first-to-file’ system under which even independent third party disclosures before the filing date may be excluded under certain circumstances. For further information on the upcoming changes to the grace period in the US, see the article From “first-to-invent” to “first-to-file”: How the first-to-file and novelty requirements under the new America Invents Act compare to Canadian patent law in this newsletter.

Some absolute novelty countries provide a “limited” grace period for certain non-prejudicial disclosures. These non-prejudicial disclosures arise only in very limited circumstances. Depending on the country, non-prejudicial disclosures may include unauthorized disclosures by parties who derive the invention from the applicant, experimental testing by the applicant, displays by the applicant at officially recognized exhibitions, presentations by the applicant before officially recognized academic societies, and/or publications by the applicant in officially recognized journals. These “limited” grace periods typically provide the applicant six or twelve months from the date of the non-prejudicial disclosure to file a patent application. In order to benefit from these “limited” grace periods some countries require the applicant to inform the patent office about the earlier disclosure upon filing the patent application. For example, the European Patent Convention (“EPC”) requires an applicant to state, when filing the European patent application, whether the invention had been disclosed and to file a supporting certificate within four (4) months. Tables 2 and 3 list examples of absolute novelty countries which provide six month and twelve month “limited” grace periods, respectively.

Grace periods are said to promote disclosure, access to knowledge, and innovation while protecting the rights of the inventor. In some areas, the value in publishing or disclosing information is undisputed. For instance, the pressure to publish academic research is high for individual inventors who rely on funding in order to carry out research. Grace periods may provide the necessary buffer to drive access to knowledge while excusing novelty-destroying disclosures of new patentable inventions. Recent proposals in Japan and South Korea to expand the scope of their grace periods (see footnotes in Table 2 below) suggests the current trend among absolute novelty countries is toward providing more generous grace periods.

For further information, please contact any one of our patent lawyers at Oyen Wiggs Green & Mutala LLP.

Table 1: A non-exhaustive list of countries which operate twelve (12) month grace periods









United States


Table 2: A non-exhaustive list of countries which operate six (6) month “limited” grace periods



European Patent Convention







Japan ¹  ²

New Zealand


South Korea ¹ ³





United Kingdom


Table 3: A non-exhaustive list of countries which operate twelve (12) month “limited” grace periods




1 Written publications by the inventor are included within the scope of non-prejudicial disclosures.

2 Anticipated amendments to the Japanese patent laws on 1 April 2012 will further broaden the scope of non-prejudicial disclosures to include sales, any exhibitions, press releases, and broadcasting.

3 Korea has entered a treaty with the US requiring Korean patent laws to provide at least a 12 month grace period for disclosures by the applicant.


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