Welcome to the new version of the Patents Manual. Please note there are changes to the numbering and sequence of the chapters and pages in the manual. You are encouraged to take the time to explore and familiarise yourself with this new structure. PCT Third Party Observations

Date Published


As of 2 July 2012, a system implemented under the PCT allows third parties to make observations on an international application if they believe that the claimed invention is either not new (lacks novelty) or is obvious (lacks an inventive step).  The key points of this PCT Third Party Observation system are as follows:

  • An observation on an international application can be submitted by a third party from the international publication date until 28 months from the priority date.
  • Once the observation has been accepted by the International Bureau (IB):
    • the applicant will be notified
    • if the ISR has not yet been received by the IB, the ISA will be notified
    • if a demand has been filed and the IPRPII has not yet been received by the IB, the IPEA will be notified
    • the observation (but not copies of the cited documents) will be available on Patentscope the next day.
  • The applicant is permitted to respond to the observation until 30 months from the priority date, but is not required to do so.
  • The observation (together with any other observations received and any responses by the applicant) will be notified to designated Offices which have asked to receive such information after 30 months from the priority date or on specific request in relation to a national phase entry.

An example of a PCT third party observation is shown in Annex K.

Dealing with PCT Third Party Observations

Examiners must take any third party observations into consideration when preparing ISRs and IPEOs/IPRPIIs. These will be listed amongst the Documents as ‘Third Party Observation’ or ‘Third Party Obs’. It is, however, unlikely that a third party observation will be available during the international search stage under normal circumstances.

During the international search stage

If a document referred to in a third party observation but was not found during the international search is cited in the ISR, the examiner may indicate this by entering “PCT third party observation submitted [Date]” in the “Documentation searched other than minimum documentation” box of the “FIELDS SEARCHED” section of the ISR.

Additionally, where a document referred to in a third party observation is cited in the ISR, the examiner is to enter “PCT third party observation submitted [Date]” in the “Earlier Search Results (if available)” field of the international SIS.  

During the IPE stage

If the IB transmits a third party observation to the IPEA in sufficient time for it to be taken into account before establishing the IPRPII, any document referred to in the observation should be considered in the same way as if it had been cited in the ISR, provided that either a copy of the document is included with the observation or is otherwise immediately available to the examiner.  The examiner is not required to comment on a document referred to in a third party observation unless the examiner considers it appropriate to cite the document.  The examiner may, if considered useful, state in Box V of the IPEO/IPRPII that third party observations submitted on specified dates have been taken into account in preparing the opinion on novelty and inventive step.

A new international SIS need not be created even if a document referred to in a third party observation is cited for the first time in the IPEO or IPRPII.   

Amended Reasons

Amended Reason Date Amended

Published for testing

Back to top