Grounds for Revocation in Art. 138 EPC are Necessary but not Sufficient Conditions - BGH Wundbehandlungsvorrichtung

Art. 138 EPC sets the conditions under which national courts may revoke national parts of European Patents:

Article 138
Revocation of European patents

(1) Subject to Article 139, a European patent may be revoked with effect for a Contracting State only on the grounds that:

...

(c) the subject-matter of the European patent extends beyond the content of the application as filed or, if the patent was granted on a divisional application or on a new application filed under Article 61, beyond the content of the earlier application as filed;

Did any of our esteemed readers ever remark the word "may" in Art. 138 EPC?

It is the basis on a BGH decision "Wundbehandlungsvorrichtung" resolving a controversy on the so-called "inescapable trap" between Art. 123(2) and 123(3) EPC within the Bundespatentgericht. While the BGH had ruled for purely national German patents that non-disclosed features may be left in a granted claim under certain circumstances  (feature is purely limiting, no "Aliud" - i.e. the amendment relates to a non-disclosed technical aspect), the 4th senate of the Bundespatentgericht had found that this cannot apply for the German parts of European Patents where the inescapable trap according to G1/93 should fall shut.

The BGH did not agree and argued that the basis of the decision in the German courts is not Art. 123 EPC but the national implementation of Art. 138 EPC, which is known as Art. II § 6 IntPatÜG. It then argues that Art. 138 EPC sets necessary but not sufficient conditions for revoking a patent and that it opens the possibility for the national court to abstain from revoking the patent although a ground according to Art. 138 exists without conflicting with Art. 123 EPC as the latter is understood by the Enlarged Board of Appeal (cf. point 49 of  the reasons, rough translation by the author).

This result is even more fascinating as the word "may" (kann) is missing in Art. II § 6 IntPatÜG, which stipulates that the patent is revoked mandatorily if the subject-matter of the European patent extends beyond the content of the application as filed.

According to the BGH, the German approach strikes the right balance between the fundamental right to protection of (intellectual) property and the aim to avoid adverse effects for third parties.