It is well known that a lack of clarity under Art. 84 EPC is not a ground for opposition listed in Art. 100 EPC, and therefore cannot be brought forward when opposing a European patent in its granted form. Nevertheless, objections under lack of clarity are still a powerful and not negligible tool for an opponent in European opposition proceedings.

This is firstly due to the fact that, while stating essentially that even an amendment that combines granted claims cannot be objected under lack of clarity, the landmark enlarged Board of Appeal decision G 3/14 confirmed that other amendments in the patent, particularly amendments of the granted claims based on features taken from the description, regularly need to fulfill the requirements of Art. 84 EPC. In addition, according to the recent Board of Appeal decision T 248/13, also a feature present in the granted claims, which however is taken out of context by amending the claims, is objectionable under Art. 84 EPC.

Secondly, according to latest statistics provided by the European Patent Office, only about 30% of all oppositions are fully rejected, i.e. only in the minority of opposition cases the opposed patent is maintained without any amendment. Accordingly, it is highly likely that at some point during European opposition proceedings, the opposed patent is amended in a way that makes clarity objections under Art. 84 EPC accessible.

One reason why clarity objections are in such cases powerful is that, if the objections are found justified by the Opposition Division, these objections cannot be healed anymore. For instance, this may happen in case that a feature of the granted claims is found to be an undue generalization, because it is inextricably linked to another feature in the original application. If this other feature is not clearly described in the description, and is successfully objected under Art. 84 EPC, the patent proprietor may be confronted with an inescapable trap. On the one hand the feature needs to be in the claim to heal the generalization issue, on the other hand it would render the claim unclear.

Another reason is that lack of clarity comes in many different shapes and colors before the European Patent Office. For instance, a lack of clarity is of course present if features of the same claim set are not compatible with each other. But also in cases where a feature of a claim can theoretically be interpreted in at least two different ways, Opposition Divisions again and again follow the objection, sometimes even disregarding an interpretation provided by the patent description.

More exotic clarity issues may also arise, for example, in case that a parameter is used to limit the granted claims. In particular, when a patent specification does not indicate how the parameter is measured. Even for a well-known parameter, several ways to measure it may exist and provide deviating result. The Board of Appeal decision T 955/07 found that a parameter is unclear even when a measurement protocol is provided, namely when the protocol is incomplete. And the Board of Appeal decision T 2086/11 found that even a complete measurement protocol may not be enough to render a parameter clear if the measurement does not produce consistent results. Here, the mean aspect ratio determined from fifty particles was considered not to reliably characterize a product consisting of thousands of particles.

It may also happen that a result obtained with a complete and workable measurement protocol is interpreted differently at different points in time. For example, if a determined measurement result was thought to correspond to a certain parameter value before a priority date of a patent, but was found to correspond to a different parameter value after the priority date of the patent, the parameter in the patent may be considered unclear.

Also for standard-related patents clarity issues may become relevant. In particular, again and again such standard-related patents are limited by introducing a reference to an industrial standard into the claims, for example, in order to distinguish from prior art relating to another standard. However, in the recent Board of Appeal decision T 1888/12, an earlier Board of Appeal decision T 0783/05 was confirmed, according to which the mentioning of a standard is not clear. This is due to the fact that it cannot be excluded, and is actually in many cases even normal, that the standard changes and evolves over time. Therefore, without providing the date of the standard, the claimed subject matter is unclear.

Even when drafting disclaimers, for instance in order to distinguish from prior art under Art. 54(3) EPC or from an accidental disclosure, the requirements of Art. 84 EPC must be met. In the recent Board of Appeal decision T 2130/11, the board generally held that the difficulty of formulating an allowable disclaimer – due to the requirements of Art. 123(2) EPC, which the disclaimer has to also meet – could not justify an exception to the application of Art. 84 EPC.

Practical Impact:

If acting in European opposition proceedings on behalf of or as the opponent, remember to raise clarity objections against amendments of a patent that allow such objections. Take a break, if for example presented with an auxiliary request based on amended claims, to assess (of course all possible objections) with serenity, and be creative about lack of clarity. If acting on behalf of or as proprietor, be careful when amending your patent.