For PCT searches and Written Opinions, prior art includes everything made available to the public by written disclosure anywhere in the world prior to an application’s international filing date. The applicant’s own work will be considered prior art – there is no one year grace period like inventors enjoy in the U.S. APA (admitted prior art) will be considered as well.
Some art cited by the PCT Examiner may not be prior art during the national phase. Understanding these differences is very important. Prior art with a priority date after the priority claim but before the international filing date can often be excluded from Examiner consideration or otherwise vulnerable to attack in many jurisdictions. This means that some prior art cited against an application may not be considered in the national application. However, failure to raise this may be deemed the applicant’s acquiescence to its consideration.
In the International Search Report (ISR) and Written Opinion, there is art that may be cited but will not be used in the Written Opinion: (1) oral disclosures/use/public exhibition before the international filing date but published after the international filing date and (2) earlier patent applications that published after the international filing date but which claim priority before the international filing date.
It is therefore important to pay attention to priority dates and international filing dates. Depending on how the priority date of the art falls between an application’s priority date and international filing date, the prior art may have an impact on the application’s examination, or it may not be considered at all by the examiner. Understanding these subtleties is critical to strategizing patent prosecution.