Lack of clarity is not a ground for opposition before the EPO, but can be raised against amendments filed during the opposition proceedings. In accordance with Article 101(3) EPC, any amendments made to a granted patent during opposition proceedings must meet the requirements of the European Patent Convention.

A new Enlarged Board of Appeal (EBA) referral asks whether an amendment made during EPO opposition proceedings can be challenged for lack of clarity if the amendment simply involves incorporating the feature of a granted dependent claim into the granted independent claim from which it depends.

Previously in T1855/07, the Board of Appeal declined to refer a question on this matter and held that a mere syntactical incorporation of a dependent claim into an independent claim cannot trigger a lack of clarity objection.

However, a few subsequent decisions, e.g.,T459/09, have held that a substantial amendment, i.e., an amendment consisting of the incorporation of a technically meaningful feature into an independent claim, in principle, justifies an unrestricted exercise of the examination power derivable from A.101(3) EPC, irrespective of whether the amendment arises from the combination of a feature from the description with an independent claim, or from the literal combination of claims of the granted patent.

In the light of these conflicting decisions, in T0373/12 (concerning EP05851833.3) the Opponent requested a stay of proceedings to seek guidance from the EBA on this matter and submitted the following question:

“Does an amendment of an independent claim during opposition proceedings hinder the examination with regard to clarity (A.84EPC), if the amended claim is a combination of an independent claim as granted with the elements of a dependent claim as granted? (Contrary to the decisions T 459/09 and T 409/10).”

The Board of Appeal has allowed the referral. However, the exact form of the referral question may be revised by the Technical Board of Appeal.