Practical Strategies for Missed Priority Deadline in International Patent Filing-Priority Restoration and Grace Period

Filing international patents through the Patent Cooperation Treaty (PCT) or Paris Convention route and claiming priority rights from domestic patents is a common strategy. However, strict deadlines apply to the validity of priority, typically 12 months from the priority date. In practice, missing these deadlines for various reasons poses significant challenges to global patent protection. This article discusses strategies for international patent layout after missing the priority deadline.

1, Measures for Missing the Priority Deadline

If the priority deadline is missed, there are two primary countermeasures:

Restoration of Priority-Lenient Priority Restoration System (LPRS)
Some jurisdictions provide a relatively lenient priority restoration system(LPRS), allowing applicants to restore priority within a certain period if specific conditions are met—such as proving the delay was unintentional and paying an official fee. Once priority is restored, there is no substantial adverse impact on the patent application in those jurisdictions.
Grace Period-Lenient Grace Period System (LGPS)
Some jurisdictions offer a grace period system that excludes an applicant's disclosures within a certain timeframe from being considered prior art against their subsequent applications (referred to as the "lenient grace period system" or LGPS). This system prevents a previously published domestic patent application from affecting the patentability of later international filings.

2, Countries/Regions with LPRS

As of the time of writing, the following countries/regions have an LPRS: Armenia, Australia, Austria, Belarus, Belize, Bulgaria, Canada, China, Chile, Djibouti, Eurasian Patent Organization (EAPO), Georgia, Guatemala, Honduras, Iraq, Jamaica, Japan, Jordan, Kuwait, Kyrgyzstan, Liberia, Malaysia, Moldova, New Zealand, Norway, Papua New Guinea, Rwanda, Saudi Arabia, Saint Kitts and Nevis, Singapore, Syria, the Antigua and Barbuda, the Dominican Republic, the United Kingdom, the United States, and Ukraine.

The restoration period is generally within 14 months from the priority date (i.e., within 2 months after the priority deadline), and a priority restoration fee is usually required.

Paris Convention Route: If an applicant files a Chinese patent application on July 1, 2023, and seeks U.S. protection, they can submit a U.S. patent application by September 1, 2024, while requesting priority restoration and paying a restoration fee ($2,100 for large entities).
PCT Route: Applicants can submit a PCT application to the China National Intellectual Property Administration (CNIPA) within the restoration period, requesting priority restoration and paying a restoration fee (1,000 RMB). If the priority restoration is granted at the international stage, no further procedures or fees are required when entering the U.S. national phase.

Note: A PCT application claiming a Chinese priority can still enter the Chinese national phase. Some key jurisdictions, such as the European Patent Office (EPO), South Korea, India, and Germany, do not recognize the LPRS.

3, Countries/Regions with LGPS

As shown below, countries with LGPS include the United States, Australia, Canada, and others. The grace period is typically 12 months (i.e., the gap between the prior publication date (X) and the overseas patent filing date (Y)). Some countries, such as Russia, have a shorter grace period of six months. Determining the overseas filing date (Y):

In countries like Australia, Y is the filing date, regardless of the priority;
In countries like the United States, if priority is claimed, Y is the priority date; if no priority is claimed, Y is the filing date.

Overseas invention patent layout in case domestic applications been published and deadline for claiming priority missed - grace period
Country/Region(Grace Period, Month)		the overseas filing date (Y)
Country/Region(Grace Period, Month)		filing date	priority or filing date
Countries/Regions with Lenient Grace Period System	U.S.(12)		√
	Australia(12)	√
	Canada(12)	√
	Rusia(6)	√
	EAPO(6)		√
	Turkey(12)		√
	New Zealand(12)	√
	Malaysia(12)	√
	Kyrgyzstan(12)		√
	Ghana(12)	√
	Guatemala(12)		√
	Honduras(12)		√
	Morocco(12)	√
Although the grace period applies, these countries exclude the patent documents that are normally published	Japan, South Korea, Singapore, Mexico, Philippines, Bolivia, Colombia, Ecuador, Latvia, Malta, Nicaragua, Panama, Paraguay, Peru, Brazil, EPO

For example, if an applicant files a domestic patent application on May 1, 2023, which was published on July 1, 2023, they could still seek U.S. patent protection by filing a U.S. application before July 1, 2024. The patentability of the U.S. application remains unaffected by the domestic publication, regardless of whether priority is claimed.

Note: Some jurisdictions (e.g., Japan, South Korea, Singapore) have grace periods but exclude ordinary published patent documents, so they are not considered to have an LGPS.

4, Practical Recommendations for International Patent Layout

If a priority deadline is missed, the following steps should be taken:

Check if the interested country has an LPRS. If available, apply for priority restoration immediately.
Assess the status of the domestic patent application.
1. If not yet published: The applicant can still file internationally without priority. While priority is lost, the unpublished domestic application will not destroy novelty for subsequent overseas applications.
2. If already published: Check if the interested country has an LGPS.
  - If LGPS applies: File within the grace period.
  - If no LGPS applies: Consider amending the patent claims or filing a new application to maintain patentability.

These recommendations provide general guidance. Applicants should verify the latest legal provisions and policy requirements and consult local professionals for advice before finalizing the international patent strategy.

Feng Shangjie (Gasoll Feng)

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