According to the established case law of the boards of appeal Art. 84 EPC has to be interpreted as meaning not only that a claim must be comprehensible from a technical point of view, but also that it must define the object of the invention clearly, that is to say indicate all the essential features thereof. All features which are necessary for solving the technical problem with which the application is concerned have to be regarded as essential features; see on this issue T 32/82 (OJ 1984, 354) and T 115/83, confirmed inter alia in T 269/87, T 391/91, T 409/91 (OJ 1994, 653), T 694/92 (OJ 1997, 408), T 1055/92 (OJ 1995, 214), T 630/93, T 61/94, T 488/96, T 1167/97, T 203/98, T 260/01, T 1069/01, T 844/02 and T 813/03. The indication of all essential features is seen as necessary to meeting the clarity requirement.
The essential features should in particular comprise those which distinguish the invention from the prior art (T 1055/92, OJ 1995, 214; T 813/03). Regarding the delimitation of essential from non-essential features, see also T 61/94, T 203/98, T 141/00 and T 260/01.
The board's opinion in T 32/82 was also confirmed in T 622/90, where it was held that lack of clarity could be caused not only by the presence of an ambiguous feature, but also by the absence of a feature which was necessary for clarity (see also T 630/93).
In T 409/91 the invention related to mineral oils containing paraffin wax. The inventors found that waxy fuels having wax crystals of sufficiently small size at low temperatures to pass through paper filters used in diesel engines could be obtained by using additives with a structure described in the application by a general formula. The claims did not mention the additives.
The board held that the claims did not define the matter for which protection was sought by reference to all its essential technical features as required by Art. 84, first sentence, EPC 1973: in the description of the application in suit the use of certain additives was presented as an essential constituent of the fuel oil composition. As this feature was missing in the claims, the board found that they defined some other invention which was not sufficiently disclosed. The board further held that the requirement that the claims be supported by the description (Art. 84, second sentence, EPC 1973) reflected the general legal principle that the extent of a patent monopoly, as defined by the claims, should correspond to the technical contribution to the art. Claims should not therefore extend to subject-matter which would still not be at the disposal of a skilled person after reading the description. Consequently, a technical feature described and highlighted in the description as being an essential feature of the invention also had to be part of the claims.
In T 1055/92 the board stated that since the primary function of a claim was to set out the scope of protection sought for an invention this implied that it was not always necessary for a claim to identify technical features or steps in detail. This primary function of the claims should be clearly distinguished from the requirement that the European patent application had to disclose the invention in such a way that it enabled a person skilled in the art to carry out that same invention. The board considered that it was sufficient if the application as a whole described the necessary characteristics of an invention in a degree of detail such that a person skilled in the art could perform the invention. This requirement, however, related to Art. 83 EPC 1973 and was not relevant to Art. 84 EPC 1973. Under Art. 83 EPC 1973 sufficient disclosure was required of a European patent application but not of an individual claim as such. A claim had to comprise the essential features of the invention; the essential features should in particular comprise those features which distinguished the invention from the closest prior art (see also T 61/94).
In T 914/02 the appellant sought to derive from the alleged sheer complexity of the proposed solution an implied use of technical means, in particular a computer. According to the board, it was doubtful as a matter of principle whether complexity could be used to disqualify an activity as a mental activity (see also under I.A.1.4.2). Rather, it would appear generally that if computer means were indeed indispensable, they should be included in the claim as an essential feature of the invention.
If from the wording of an independent claim it must be concluded that a solution of the problem of the invention is achieved by not needing a step, whereas this very feature according to the description cannot be abolished, but is necessary for a workable solution, then such a features is to be considered, so the board in T 888/07, an essential feature of the invention. An independent claim missing this feature is therefore neither clear, nor supported by the description.
In T 818/03 the board considered that a method claim which did not state sufficiently clearly the steps by which a particular result was achieved might still be considered clear provided the result to be achieved was clearly defined, and a claim which defined a method of achieving some less than clearly defined result might also still be considered clear provided the steps that needed to be taken to achieve that result were sufficiently clearly defined. However, a claim must be considered to lack clarity if, as here, it set out insufficiently clearly both the necessary parameters of the method and the relevant characteristic features of the result.
In G 1/04 (OJ 2006, 334) the Enlarged Board recalled that an independent claim within the meaning of R. 29 EPC 1973 should explicitly specify all of the essential features needed to define the invention, and the meaning of these features should be clear for the person skilled in the art from the wording of the claim alone. The same should apply mutatis mutandis in respect of a claim relating to the subject-matter excluded from patent protection under Art. 52(4) EPC 1973 (Art. 53(c) EPC). These requirements served the overriding purpose of legal certainty.
The Enlarged Board took the view that a diagnostic method within the meaning of Art. 52(4) EPC 1973 had an inherent and inescapable multi-step nature. If diagnosis as the deductive medical or veterinary decision phase was a purely intellectual exercise, the feature pertaining to the diagnosis for curative purposes and the features relating to the preceding steps which were constitutive for making the diagnosis represented the essential features of a diagnostic method within the meaning of Art. 52(4) EPC 1973. Thus, in order to satisfy the requirements of Art. 84 EPC 1973, an independent claim relating to such a method must include these features.
The essential features necessary for clearly and completely defining a particular invention were for the most part of a technical nature. But, if a non-technical feature was to be regarded as constitutive for defining the invention, it must likewise be included as an essential feature in the independent claim. Thus, although diagnosis stricto sensu was a purely intellectual exercise unless it was carried out by a device, the feature pertaining to it was such an essential feature as to be included in the independent claim. The same applied to a feature relating to a method step of a non-technical nature belonging to the preceding steps which were constitutive for making the diagnosis for curative purposes. As regards, in particular, the non-technical feature pertaining to diagnosis for curative purposes, it was to be included as an essential feature in the respective independent claim if its essentialness was unambiguously inferable from the respective European patent application or European patent as a whole. This was the case if the application or patent in question disclosed a method for obtaining findings of diagnostic relevance which allowed the attribution of the detected deviation to a particular clinical picture (on the principal issues of this decision, see Chapter I.B.4.5).
In decision T 923/08 the board decided as follows: If a method for recording measurements on the human or animal body necessarily entails a surgical step in order to fix to the human or animal body a measuring device which is indispensable for performing the method, this step has to be deemed an essential feature of the method and is comprised in such a method, even if the claim contains no method feature explicitly directed to it. Such a method is excluded from patentability under Art. 53(c) EPC.
The exclusion of such a surgical step, whether by stating that the surgically attached measuring device was already fixed to the body before the start of the method or whether by use of a disclaimer, breaches Art. 84 EPC 1973 because such a process claim does not then include all the essential features of the claimed invention.