Article 84 of the European Patent Convention requires patent claims to be “clear” in scope, and examiners at the EPO often raise objections if they feel that an application does not meet the requirement for clarity.
In post-grant opposition proceedings, there is no corresponding requirement: lack of clarity of claims is excluded from the grounds for opposition.
However, it is common for a patent to be amended in the course of opposition proceedings, and Article 101(3) EPC states that the opposition division must examine whether the amended patent meets the requirements of the EPC in coming to its decision to maintain or revoke the patent. This has led to the recurring issue of whether this means the opposition division or board of appeal must examine the amended claims for clarity as well the main substantive issues such as novelty and inventive step.
There have been diverging decisions on this question by EPO Boards of Appeal: a first, “conventional” line of jurisprudence, exemplified by Decision T301/87, and a second, “diverging” line of jurisprudence, represented by T1459/05 and T459/09. Consequently, questions on this issue were referred to the EPO’s Enlarged Board of Appeal. In particular, the Enlarged Board was asked to decide whether it was allowable to examine the clarity of amended claims in cases where elements of a dependent claim were added to an independent claim, and if so to clarify how extensive that clarity examination ought to be.
The Enlarged Board has answered that in considering whether, for the purposes of Article 101(3) EPC, a patent as amended meets the requirements of the EPC, the claims of the patent may be examined for compliance with the requirements of Article 84 EPC only when, and then only to the extent that, the amendment introduces non-compliance with Article 84 EPC.
The Enlarged Board thus approves the conventional line of jurisprudence. According to this approach, when claims are amended in opposition proceedings, lack of clarity objections cannot be raised if the objections “do not arise out of” the amendments made. However, the Enlarged Board disapproves the line of jurisprudence as exemplified by T472/88, in which “arises out of” was given a broad construction based on the Oxford Dictionary definition of arise: “originate, be born, result from, come into notice, present itself” such that the definition might extend to include “concealed” lack of clarity which was then “made visible” after the amendment.
The Enlarged Board also disapproves the line of “diverging” jurisprudence, represented by T 1459/05 and T 459/09. T1459/05 said that clarity of a combination of a dependent claim and an independent claim was to be examined as an exception, due to the fact that the added feature was unclear; T459/09 said that examination of clarity was justified when the claims were amended with a technically meaningful feature.
The Enlarged Board’s ruling will limit the extent to which consideration of the clarity of amended claims can be raised in opposition proceedings. Whether that is a good or bad thing depends, of course, on whether one is the patent proprietor or an opponent. Life will be made somewhat easier for those seeking to fight off an opponent by making amendments to the patent claims, while for opponents the range of issues they can raise in attacking a patent will be more restricted.