5. Deutlichkeit und Vollständigkeit der Offenbarung

In T 878/23 claim 1 of the main request concerned a product claim. The claimed composition comprised an amino acid combination selected from seven combinations containing two or three amino acids selected from cysteine, alanine, lysine and arginine. Claim 1 further specified that the composition contained specified concentrations (amounts) of each of lysine, alanine and arginine (from "8 to 20 wt.%") and cysteine (from "2 to 10 wt.%") based on the composition's total dry weight. Claim 1 thus defined minimum and maximum amounts for each of the four indicated amino acids in the claimed composition. Dependent claim 4 further specified that the composition of claim 1 contained a "total amino acid concentration ... in the range from 3.5 to 36.5 wt%, based on the total dry weight of the composition". Claim 4 added thus a further limit to the composition as defined in claim 1 concerning the used total minimum and maximum concentration (amount) of amino acids.

The board observed that the minimum concentration of amino acids that had to be present in the claimed composition differed between the ranges indicated in claims 1 and 4. The board explained that since a dependent claim (here claim 4) contained more technical features than an independent claim (here claim 1) on which it depended, the subject-matter of a dependent claim was generally more limited than that of the independent one. However, in the case in hand, the compositions specified in claim 4 were broader than those of claim 1, since claim 4 allowed the presence of lower amino acid concentrations in the claimed composition than claim 1. Since the concentration ranges defined in claims 1 and 4 were mutually exclusive, i.e. incompatible, over a substantial part of their ranges, the skilled person could not technically prepare the composition as defined in claim 4 across substantially the whole breadth claimed, even if taking common general knowledge into account. The subject-matter of claim 4 was therefore insufficiently disclosed.

While appellant I (the patent proprietor) admitted that there was an inconsistency between the concentration ranges indicated in claims 1 and 4, it argued that this inconsistency exclusively resulted in a clarity issue (Art. 84 EPC). The board disagreed. The board explained that the decisive issue did not concern an ambiguity of the scope of protection of the claimed invention, as would be the case, for example, if a specific compound would be defined by an unclear parameter. In the case in hand, standard amino acids were used for preparing the claimed composition. These were specified by standard concentration ranges. The methods for determining these concentrations were standard too. Nevertheless, despite these clear instructions in claims 1 and 4, the skilled person could not prepare the claimed composition over substantially the whole breadth of claim 4 due to the at least in part incompatible or mutually exclusive concentration requirements indicated in claims 1 and 4. Claim 4 thus contained no "forbidden area", but an area which could not be prepared for technical reasons.

The board concluded that Art. 100(b) EPC prejudiced the maintenance of the patent as granted. Since the objections under insufficiency indicated above for claim 4 as granted applied likewise to auxiliary requests 1 to 18, the board held that auxiliary requests 1 to 18 did not comply with the requirements of Art. 83 EPC.

In case T 1977/22, the opposition division revoked the patent arguing that the definition of certain parameters in terms of an open-ended range rendered the invention insufficiently disclosed, as these parameters could not be reproduced over the whole scope of the open-ended side.

The board addressed this question by first reviewing the landmark decisions which gave rise to the principle of "reproducibility over the whole claimed scope" (T 435/91, T 292/85, T 226/85, T 409/91, and G 1/03), then reviewing the case law specifically dealing with open-ended range desiderata and sufficiency of disclosure, before addressing the question of how to apply the general requirement of "reproducibility over the whole scope“ to the specific case of inventions defined in terms of an open-ended range desideratum, and finally by applying the proposed criteria.

More specifically, the board stated that the main idea behind the principle of reproducibility over the whole scope is that where an invention is defined as a combination of process and/or structural features (A+B) to achieve a certain result or desideratum (X), the skilled person should be enabled to achieve the result (X) over the whole scope of the claim, which is intended to ensure that the breadth of the claimed invention is commensurate with the teachings of the patent, i.e. that the scope of protection is restricted to the actual technical contribution of the patent. According to the landmark decisions, the assessment should be based on balanced criteria, avoiding unrealistic requirements, such as excluding all non-working embodiments or providing instructions to identify every possible working embodiment, while still ensuring that the claim includes all features essential to achieving the defined desideratum and that the breadth covered by the functional definition is commensurate with the teachings of the patent.

The board then turned to review in detail the case law dealing with "open-ended ranges desideratum and sufficiency of disclosure" (point 3 of the Reasons). Following this, the board dealt with the key question of the reproducibility over the whole scope of open-ended ranges (point 4 of the Reasons). It stated that where the desideratum was, as in the present case, defined in terms of an open-ended range for a physical parameter of a product, the problem of reproducibility over the whole scope was analogous to that addressed in the landmark decisions, with the key distinction being that the inclusion of non-working embodiments may also stem from the desideratum itself, as the open definition broadens the claimed scope in such a way as to implicitly encompass non-working embodiments, i.e. irreproducible parametric values (unrealistically high) and/or yet-to-be-discovered alternatives (values only achieved with inventive skill). That the claim covered non-working embodiments was not in itself sufficient to conclude that the invention would not be reproducible over the whole scope. The key issue was the burden to be applied for assessing whether the teachings in the patent would enable the skilled person to reproduce the open-ended range over the whole scope of the open-ended side. In this respect, the open-ended definition should not be interpreted literally as requiring teachings enabling the skilled person to achieve any parametric value in the upward direction; interpreting the concept literally would impose a technically unsurmountable burden and would be in contradiction with the landmark decisions that it was not required that all non-working embodiments be excluded or that every working embodiment be enabled. Instead the board concluded that open-ended ranges should be interpreted as equivalent to a directional requirement to adjust and increase the parameter to obtain values as high as achievable (beyond the lower end value) with the structural and/or process features defined in the claim (see details point 4.6.7of the Reasons; also Catchword and conclusions point 4.13). By making routine adjustments within the scope of these features, it was possible to achieve parametric values exceeding the lower-end limits.

The differing outcomes in the case law (open-ended ranges) did not stem from any fundamental divergences.