Correcting a European Patent Application

Under Rule 139 EPC, second sentence, mistakes concerning the description, claims or drawings, of a pending European patent application may be corrected on request.

EPO case law states that, in order to determine if such a correction is allowable under Rule 139 EPC, a two-step approach must be followed:

It must be established that it is obvious that an error is in fact present in the document, and that the incorrect information is objectively recognisable by the skilled person using common general knowledge.

It must be established that the correction of the error is obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction.

An example of a successful correction under Rule 139 EPC is a correction of “72EF” to “72°F”, which was found to be allowable because it was the only possible correction having a technical meaning in the context of the document being corrected. It was found that the skilled person would have immediately considered that “F” meant “Fahrenheit”, and would have made the correction accordingly.

However, if it can be shown that the skilled person would have contemplated several different corrections, only one of which is offered as the correction, then it is not immediately evident that nothing else would have been intended. Accordingly, in this case, the offered correction would not be allowed.

An example of an unsuccessful correction under Rule 139 EPC is a correction of a feature “vanadium” to “vanadium oxide”, which was found to be unallowable because the proposed correction was only one of several options. As long as there is at least one further possibility of correction, step (ii) above is not fulfilled.

Any correction to the description, claims, or drawings of a European patent application must also comply to the requirements of added subject matter, Article 123(2) EPC. In other words, an error may be corrected under Rule 139 EPC, second sentence only within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge and seen objectively and relative to the date of filing, from the whole of these documents as filed.

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