4. Correction of errors in the description, claims and drawings – Rule 139 EPC
4.3. No replacement of the description under Rule 139 EPC
Decision G 2/95 (OJ 1996, 555) decided that the complete documents forming a European patent application could not be replaced under R. 88 EPC 1973 (R. 139 EPC). The interpretation of R. 88 EPC 1973 (R. 139 EPC) had to be in accord with Art. 123(2) EPC 1973. See G 3/89 (OJ 1993, 117) and G 11/91 (OJ 1993, 125). See also IV.A.5.5.2.
In J 5/06 and J 16/13 the Legal Board held that this equally applied to the exchange of a description. This followed from the principle that the filing date is inseparable from the description, since it is obvious that allowing an exchange of "only" the description by way of correction would directly result in the separation of the filing date from the description.
In J 3/21, the Legal Board observed that the ban on the replacement of the description by way of correction, established in G 2/95 on the basis of Art. 123(2) EPC and further developed in e.g. J 5/06 and J 16/13, was categorical and followed from the principle reflected in R. 40(1)(c) EPC that the accorded filing date is inseparable from the description as originally filed. An exchange of the description by way of correction would directly result in the separation of the filing date from the description in contravention of Art. 123(2) EPC.
According to T 1963/17, the reason for this is simply that in light of the infinite possibilities of drafting a description, it is not obvious to a skilled person how an amended description should look like. The board observed that in the case in hand, in which the originally filed description did not match the claims and applicant requested to substitute the originally filed description, it may not even have been obvious to a skilled person which invention the applicant intended to pursue. Moreover, the board agreed with J 27/10 that an interpretation of R. 56 EPC that some, or all, of the description that was originally filed in order to obtain a filing date could be amended, replaced or deleted is incorrect. See also chapter IV.A.5.4.2.