Although, lack of clarity can arise through contradictions or ambiguity (T 373/12), ambiguity may also lead to an insufficiency objection under Art. 83 EPC in cases where ambiguity deprives the person skilled in the art of the promise of the invention in practice (T 608/07). Consequently, there is a delicate balance between Art. 84 EPC (clarity) and Art. 83 EPC (enablement).
In a recent decision of May 2014, the Boards of Appeal have refocused on the interpretation of the relationship between Art. 84 EPC and Art. 83 EPC (T 754/13).
Art. 84 EPC requires that “The claims shall define the matter for which protection is sought. They shall be clear and concise, and be supported by the description”.
Art. 83 EPC requires that “A European patent application must disclose the invention in a manner sufficiently clear and complete to be carried out by a person skilled in the art”. The same applies for a European patent under Art. 100 (b) EPC.
According to the present decision of the Boards of Appeal, the term “clear” has two different meanings under Art. 84 EPC: First of all, the claims per se must be clear in themselves when read by a person skilled in the art without any reference to the content of the description. Further, the claims have to be clear for the sake of legal certainty since their purpose is to enable the protection conferred by the patent to be determined because a potential infringer should be enabled to determine whether or not he or she is working within the scope of the claim or not. This, however, requires that the scope of protection must be determined “without undue burden”.
To sum up, the requirement “without undue burden” is not only a prerequisite to carry out the claimed invention by a person skilled in the art using the general knowledge under Art. 83 EPC but also to define the matter for which protection is sought under Art. 84 EPC, i.e. the extent or scope of protection.
Consequently, both conditions of “undue burden” should be considered when drafting a European patent application or preparing an opposition against a European patent.