Following publication of the European patent application under Art. 93, any person may present observations concerning the patentability of the invention. Although lack of novelty and/or inventive step are the most common observations, third-party observations 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)).
Such 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 may not be a party to the proceedings before the EPO. The web interface provided by the EPO is the preferred means of filing such observations (see OJ EPO 2011, 418 and OJ EPO 2011, 420).
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 period to be specified; otherwise the evidence will be disregarded.
Although the third party is sent acknowledgment of the receipt of his observations, the EPO does not specifically inform him 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 respective office action from the EPO (e.g. in a communication or in the intention to grant) and will thus be visible to the public.
The observations are communicated to the applicant or proprietor without delay and he may comment on them. If they call into question the patentability of the invention in whole or in part, they must be taken into account in any proceedings pending before a department of the EPO until such proceedings have been terminated, i.e. they must be admitted to the proceedings. If the observations relate to alleged prior art available other than from a document, e.g. from use, this should be 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 after the conclusion of proceedings will not be taken into account and will simply be added to the non-public part of the file.