PA 02/2020: Meeting the requirements for restoration of the right of priority under the “due care” criterion

WARNING: Although the information which follows was correct at the time of original publication in the PCT Newsletter, some information may no longer be applicable; for example, amendments may have been made to the PCT Regulations and Administrative Instructions, as well as to PCT Forms, since the PCT Newsletter concerned was published; changes to certain fees and references to certain publications may no longer be valid. Wherever there is a reference to a PCT Rule, please check carefully whether the Rule in force at the date of publication of the advice has since been amended.

Q:  For reasons beyond my control, I failed to file an international application within the 12‑month priority period, and was only able to file it two days after the expiration of that period.  The designated Offices where I intend to enter the national phase require, in order to restore the right of priority, that the applicant’s failure to file within the priority period occurred in spite of due care required by the circumstances having been taken.  I would like to know what I need to submit to maximize the likelihood that the receiving Office, which checks that criterion, makes a positive finding as to the due care criterion.  Also, could you give me some idea of the kind of circumstances in which due care could be considered to have been taken?

A: Full details on how to make a request for restoration of the right of priority were given in the Practical Advice in PCT Newsletter No. 09/2015 at:

It is recalled that, in addition to requesting restoration of the right of priority, either under Box No. VI of the request form (PCT/RO/101) or by way of a letter to the receiving Office submitted within the applicable time limit under PCT Rule 26bis.3(e)1, you must also furnish within that same time limit a “statement of reasons” explaining why you failed to file the international application within the priority period (PCT Rule 26bis.3(b)(ii)).  The statement of reasons should take into consideration the restoration criterion which you seek to satisfy, and it should preferably be accompanied by a declaration or other evidence in support of the statement (PCT Rule 26bis.3(b)(iii)). 

In order to meet the “due care” criterion (as opposed to the less stringent criterion of “unintentionality”, for which a simple declaration is generally sufficient), the statement of reasons should describe in detail the specific facts and circumstances that led to the late filing, as well as any remedial or alternative steps taken to attempt a timely filing of the international application.  Generally, the standard of having exercised “due care” within the meaning of PCT Rule 26bis.3(a)(i) can only be met if the applicant has taken all measures which a reasonably prudent applicant would have taken.

In determining whether the applicant exercised the “due care” of a reasonably prudent person, the receiving Office considers the facts and circumstances of each particular case.  It is not sufficient for an applicant to demonstrate that, in general, he/she has taken all precautions to adhere to time limits for filing international applications.  Instead, the applicant must show that he/she exercised all “due care” for the particular application in question.  The receiving Office will engage in a factual analysis of the applicant’s specific acts related to the filing of the international application up to the expiration of the priority period. 

Where the applicant is represented by an agent, both the applicant and the agent must show that they exercised “due care” in order to satisfy that criterion.  As far as the applicant is concerned, the appointment of a qualified representative would, under normal circumstances, generally be sufficient to satisfy the criterion of “due care”. 

While each receiving Office engages in its own case‑by‑case analysis, the PCT Receiving Office Guidelines ( contain examples of circumstances where a receiving Office may find the “due care” criterion to be satisfied.  The examples in the Guidelines will give you an idea of how detailed, in your situation, the statement of reasons would need to be and help you determine what, if any, evidence should be submitted to support your statement. 

For example, in the case where the failure to meet the priority period was due to human error by the agent’s or applicant’s administrative staff (non-attorneys such as assistants or paralegals) who has been entrusted with the performance of certain administrative tasks:  

“A prudent applicant or agent carefully chooses, trains and monitors the work of a reliable, experienced, adequately trained and supervised employee.  A human error by an assistant in the docketing, monitoring, preparation or filing of the international application is not attributed to the applicant or agent if the applicant or agent can show that “due care” was exercised in the management of the assistant and the failure to file within the priority period in this particular case was an isolated human error.  In the statement of reasons, the applicant or agent should usually outline the number of years the assistant has been entrusted with the particular task, the level of training and supervision provided to the assistant and whether the assistant has performed all his [or her] duties diligently in the past.” [PCT Receiving Office Guidelines, paragraph 166M(f)]

Further examples of common reasons for failure to file the international application within the priority period can be found at:

It should be noted that, while the same standard cannot be expected from an individual inventor or a small or medium-sized enterprise, any applicant or agent is expected to set up an efficient and reliable reminder, supervision and back‑up system which corresponds to best practices in the field. 

If the receiving Office finds that the statement of reasons and any evidence provided by the applicant is not sufficient to make a determination as to whether the relevant criterion would be fulfilled, it will, before refusing the request for restoration, inform the applicant of its intention to refuse restoration of the right of priority and give the applicant the opportunity to provide any observations, evidence or declarations within a (further) time limit set by the Office by issuing Form PCT/RO/158 (Notification of Intended Refusal of Request to Restore Right of Priority and/or Invitation to Furnish Declaration or Other Evidence).  After the expiration of the applicable time limit, the Office will make a determination as to whether the criterion in question has been met or not, based on any reply received, and notify the applicant by issuing Form PCT/RO/159 (Notification of Decision on Request to Restore Priority).

Where a statement of reasons is not sufficient, it may be supplemented as described above, but if no statement of reasons was provided at all during the time limit indicated in PCT Rule 26bis.3(e), please be aware that the receiving Office will normally refuse the request to restore the right of priority, indicating that the refusal is because the statement of reasons was missing.

If you are concerned about any possible publication by the IB of confidential documents submitted to the receiving Office as evidence relating to your request for restoration, the receiving Office may, upon receipt of a reasoned request by the applicant, or on its own decision, not transmit to the IB such evidence where it is considered confidential, and that information would consequently not be made publicly available (PCT Rule 26bis.3(h-bis)).  Examples of information which might qualify under that Rule are private details of persons involved in the late filing of the international application, such as the name of a paralegal, or medical certificates stating the nature of an illness.  You may even decide to already expunge from the document from the start such confidential information which is not necessary for the receiving Office to decide on the request for restoration.

For information on which Offices accept requests for restoration of the right of priority and which criterion (if they only apply one criterion) they apply, as well as information on any fees payable to the Office for making such a request, please refer to the table at:

Please note that applicants may also request restoration of priority rights in the national phase (PCT Rule 49ter.2), to the extent that the designated Office accepts such a request and applies the criterion concerned.  Any such request must be filed with each designated Office concerned within one month from the applicable time limit under PCT Article 22.  More information can be found in the restoration table at the above‑mentioned link.

  1. The time limit under PCT Rule 26bis.3(e) is two months from the expiration of the priority period, unless early international publication has been requested earlier than this, in which case it is prior to the completion of technical preparations for international publication.

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