This decision is a good refresher on how the EPO looks at the requirements of clarity under Article 84 EPC. The appeal lies from a decision of the Examining Division.
2. Clarity (Article 84 EPC)
Article 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".
2.1 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. It is further constant jurisprudence of the Boards of Appeal that 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. Thereby a potential infringer of the subject-matter of the claims should be enabled to determine whether or not he is working within the scope of the claim. The latter brings with it that the skilled person should be able to establish to a sufficient extent the demarcation of the scope of the claim (i.e. its extent of protection) without undue burden. In the context of determining the scope of protection of a claim it has additionally to be considered that Article 84 EPC is not a ground of opposition (see Case Law of the Boards of Appeal, 7th edition 2013, sections II.A.1.1 to 1.5 and II.A.3.1) and therefore needs proper attention in examination proceedings.
The Board then discusses in detail the several features of the claims at issue, which comprise a mixture of functional features and technical features and comes to the following:
2.3.8 Taking account of the above, the Board considers that, although the experiments described in the application appear to be very simple, there exists an undue burden for the skilled person since he has to carry out at least a small research program based on said seven parameters a) to g) to ascertain the boundaries of the scope of claim 1 of the main request.
The Board further considers [..] that the very broad subject-matter of claim 1 of the main request, which encompasses all kinds of gases and liquids, is not supported - as required by Article 84 EPC - by the [..] application as originally filed with respect to the small number of only two examples which were only made with water (optionally in combination with a small amount of a surfactant, i.e. Tween 80) as said liquid in combination with an unspecified gas (see point 2.3.5 above).
Read the full decision here.