3. Observations by third parties 

Following publication of the European patent application under Art. 93, any person may present observations concerning the patentability of the invention. Although third-party observations most commonly relate to lack of novelty and/or inventive step, they may also be directed to clarity (Art. 84), sufficiency of disclosure (Art. 83), patentability (Art. 52(2) and Art. 52(3), Art. 53 or Art. 57) and unallowable amendments (Art. 76(1), Art. 123(2) and Art. 123(3)).

The observations must be filed in writing in English, French or German and must include a statement of the grounds on which they are based. The person filing them must not be a party to the proceedings before the EPO. They should preferably be filed via the online form provided by the EPO (see OJ EPO 2025, A71OJ EPO 2017, A86). They may be filed anonymously.

Documentary evidence and, in particular, publications submitted in support of the arguments may be filed in any language. However, the EPO may request that a translation into one of its official languages be filed within a specified period or else the evidence will be disregarded.

Although third parties are sent acknowledgment of the receipt of their observations (if these were not filed anonymously), the EPO does not specifically inform them of any further action it takes in response to them. However, the outcome of the evaluation by the competent division will briefly be indicated in the related EPO action (e.g. in a communication or in the intention to grant) and will thus be visible to the public.

The observations, including those filed anonymously, are put on file. They are communicated without delay to applicants or proprietors, who may comment on them. If they call into question the patentability of the invention in whole or in part, the examining or opposition division will take them into account in the next EPO action. If the observations relate to alleged prior art available other than from a document, e.g. from use, this is taken into account only if the alleged facts either are not disputed by the applicant or proprietor or are established beyond reasonable doubt.

Observations by third parties received in examination after dispatch of a Rule 71(3) communication but before the decision to grant (EPO Form 2006A) has been handed over for notification to the parties to the EPO postal service will be considered by the examining division. If they are relevant, the examining division will resume examination. Otherwise, brief substantive feedback will be provided in the file.

Observations by third parties received after the decision has been pronounced in oral proceedings (e.g. in the case of a refusal or in opposition) or issued in written proceedings and handed over to the EPO postal servicefor notification to the parties (e.g. in the case of a grant decision or if, in opposition, no oral proceedings were held), will be put on file without any consideration of their content.

Observations by third parties received once proceedings are no longer pending will not be taken into account or made available for file inspection. They will, however, be made available for file inspection and considered if the proceedings before the EPO become pending again, e.g. at the start of any opposition or limitation proceedings.

The EPO will make every effort to issue its next action within three months of receipt of third-party observations under Art. 115 by the examining division, provided the observations are substantiated and have not been filed anonymously. Where the observations are received at a time when a reply from the applicant to a communication is outstanding, this period starts from receipt of the reply at the EPO.

The EPO will generally apply the practice it follows for third-party observations filed in the Euro-direct procedure mutatis mutandis to third-party observations filed during the international phase once the Euro-PCT application has entered into the European phase.

Where third-party observations were filed during the international phase, the EPO as designated/elected Office will consider their content once they become available to it after the application's entry into the European phase. The examining division will make every effort to issue its next action within three months of expiry of the period under Rule 161, but only on condition that the third party has clearly expressed a wish for expedited handling in the European phase, that the observation was filed non-anonymously and that it was substantiated. A third party wishing to achieve this result in the European phase must therefore make this clear in the observation or file the observation with the EPO as designated/elected Office.