EPO decision reinforces strict approach to "added matter"

A recent decision (T2017/07, published April 2010) from the Technical Board of Appeal of the EPO highlights how an apparent limitation to a patent claim can actually have the effect of broadening the claim beyond its scope as granted (Article 123(3) EPC). The decision also illustrates how strictly the added matter provisions of European practice are being interpreted by the EPO (Article 123(2) EPC).

In Europe, a patent specification may be amended provided that there is basis for the amendment in the application as originally filed (Article 123(2) EPC). Once granted, however, a patent cannot be amended in such a way as to broaden its scope (Article 123(3) EPC).

In T2017/07, a patent was granted with a claim to a composition comprising 0.5 to 50 weight % of a chemical compound having three to five carbon atoms. During opposition, the patentee amended the claim to a composition comprising 0.5 to 50 weight % of a chemical compound having three carbon atoms. On the face of it, this appeared to restrict the scope of the claim. However, the Board held that, while the claim as granted limited the amount of chemical compounds having e.g. four or five carbon atoms that could be present, the amended claim did not. Accordingly, the amended claim was broader than the claims as granted, in contravention of Article 123(3) EPC.

The patentee then tried to amend the claim to indicate that a chemical compound having three carbon atoms was the sole chemical compound having three to five carbon atoms. The amendment avoided the Article 123(3) EPC objection above, as it excluded the possibility of compounds having four or five carbon atoms from being present. The Board, however, held that there was no basis for the amendment. Although the original application described a compound having three carbon atoms as being preferred, the Board held that this did not necessarily mean that it should be used as the sole component. Although some of the examples illustrated the use of the compound as the sole component, the Board held that this was only in the context of specific, exemplified compositions. In the Board’s view, there was no basis for isolating this feature from these specific examples and generalising it across the scope of the claim. The amendment, therefore, was found to add matter (Article 123(2) EPC).

As a last resort, the patentee then tried to limit the claims to a composition consisting of 0.5 to 50 weight % of a chemical compound having three carbon atoms and various optional components that were listed in the claim. The consisting of language excluded the presence of components that were not explicitly mentioned in the claim. Although the optional components listed in the claim were described in the original application, the Board held that the original application did not suggest that the list of optional components was exhaustive. By including the list in a claim in the consisting of format, the list of optional components had been made exhaustive, since other unspecified components could no longer be present in the claimed composition. As this was not contemplated by the original disclosure, the Board held that the amendment added matter, contrary to the requirements of Article 123(2) EPC.

This decision highlights how an apparent restriction of a claimed feature in one respect can result in the claim being broadened in another respect. It also reinforces how strictly the added matter provisions can be interpreted by the EPO. Once an application is filed, a patentee’s ability to amend his specification is restricted to amendments that are directly derivable from the original disclosure. We therefore recommend that European patent specifications contain a comprehensive description of the preferred features of the invention, which are described both singularly and also in combination, so that the disclosure of these features can be relied upon to provide useful basis for future amendments.

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