Making Amendments to a PCT Patent Application

We sometimes receive requests to make changes to an already-filed PCT patent application. Various opportunities exist during prosecution for amending a PCT patent application depending on a nature and type of change requested. Obvious mistakes in the description, claims, or drawings of a PCT application can be rectified if correction of the mistake is requested within 26 months from the priority date of the PCT application. Mistakes are considered to be obvious if “something else was intended than what appears in the document concerned and that nothing else could have been intended than the proposed rectification.” PCT Rule 91.1(c).

However, an Applicant who wishes to make amendments to the claims of a PCT application that do not correct an obvious mistake can file the amendments under Article 19 prior to the expiration of 16 months from the priority date of the PCT application or two months from the mailing date of an International Search Report and Written Opinion, whichever is later. Additionally, amendments to the claims, as well as the description or drawings, of a PCT application can also be made after the Article 19 deadline passes, as long as a Demand for International Preliminary Examination is timely filed. Specifically, the Demand must be filed prior to expiration of 22 months from the priority date of the PCT application or within three months from the mailing date of the International Search Report and Written Opinion. Any desired amendments can then be filed at the time of filing the Demand or in reply to any notification mailed during International Preliminary Examination.

Finally, amendments can also be entered via a preliminary amendment upon entering the national stage in one or more countries, when the time has passed for filing amendments during the above-identified periods. However, unlike the amendments discussed above, a preliminary amendment must be filed in each country in which the national stage has been entered.

In summary, any amendments to the description or drawings of a PCT application must accompany a Demand unless the amendments correct an obvious mistake. However, claim amendments can be filed without the filing of a Demand, as long as the claim amendments are filed prior to the expiration of 16 months from the priority date of the PCT application or two months from the mailing date of an International Search Report and Written Opinion, whichever is later. Also, amendments to the description, claims, or drawings can be filed with a national stage entry application, but the amendments must be made in each country in which the national stage has been entered.