National rights of earlier date are not comprised in the state of the art (Art. 54) for the purposes of the EPO examination for patentability. However, under Art. 139(2), national rights of earlier date can be invoked, after the grant of the European patent, in national proceedings as a ground for revocation. These rights represent exceptions to the uniformity of European substantive patent law. Where national rights exist, therefore, the applicant or proprietor has a legitimate interest in submitting different claims to ensure that the patent granted will not be partly revoked in some contracting states (see Rule 80 and Rule 138). The filing of different claims is, however, neither required nor suggested.[Art. 139(2); ]

If an applicant or proprietor produces evidence in examination/opposition proceedings of the existence of pertinent national rights of earlier date in a particular (designated) contracting state, it is appropriate to admit separate claims for the contracting state in question. The evidence must be in the form of a specification or, where applicable, a copy of the utility model or utility certificate or of the application for it (see Art. 140); this is necessary to prevent unjustified deviation from the unity of the European patent.

In opposition proceedings, a national right of earlier date is neither a ground for opposition nor a ground for revocation. Hence, it is not admissible for an opponent to introduce a national right of earlier date into opposition proceedings to support a novelty attack.

The effect of the national right of earlier date is determined by the relevant national provisions. The examining or opposition division does not decide whether the applicant or proprietor has limited the scope of the application/patent to the extent required to overcome the effect of the national right (see G‑IV, 6). That is the responsibility of the applicant or proprietor.

The examining or opposition division must check that the separate claims do not contravene Art. 123(2) and Art. 123(3), and that they meet the other requirements of the EPC. The same applies to a separate description (see H‑III, 4.1).

Moreover, in general, there is no justification for a separate description. However, at a suitable point in the preamble to the description, preferably in a separate paragraph following the information pursuant to Rule 42(1)(a), a reference to this situation must be made, for example along the following lines:

"With reference to ... (e.g. earlier application No. ... in ...), the applicant has voluntarily limited the scope of the application /patent for... (contracting state) by submitting separate claims for this (these) state(s)."