3.2. Relative qualities and vaguely formulated claims

In the key decision T 728/98 (OJ 2001, 319) the board held that it followed from the requirement of legal certainty that a claim could not be considered clear within the meaning of Art. 84 EPC 1973 if it comprised an unclear technical feature (here "substantially pure") for which no unequivocal generally accepted meaning existed in the relevant art. This applied all the more if the unclear feature was essential for delimiting the subject-matter claimed from the prior art (see also T 1399/11, T 1702/15). According to the board in T 869/20, T 728/98 did not conclude that clarity should only be examined when the unclear feature is the sole differentiating feature, but simply stressed that in such case the requirement of clarity is particular important to ensure legal certainty.

Likewise in T 226/98 (OJ 2002, 498) the board held that the feature "as a pharmaceutical product" for defining a pharmaceutical standard of purity in a claim related to a product as such (here, famotidine form "B"), rendered said claim unclear in the absence of a generally accepted quantitative definition for the purported standard of purity. Also in T 174/02 ("[in] quick [succession]"), T 1640/11 ("value"), T 842/14 ("accurate"), T 1963/17 ("substantially simultaneously"), T 362/17 ("brief [history of spoken words]"), T 1903/19 ("low intensity"), T 1152/21 ("appropriate temperature", "about 70°C", "about 3 hours") the boards ruled that the relative terms at issue were unclear.

In T 1469/20 the board held that the terms "inexpensive", "swift", "wide variety" and "pleasant association" in claim 1 were not clear. The fact that the claim could be interpreted, essentially by disregarding the relative and subjective terms which were not clearly limiting, did not mean that the claim could be allowed as it stood. The board pointed out that clarity is a requirement separate from novelty and inventive step, and allowing unclear terms to remain in the claim places an undue burden on the reader seeking to determine the scope of protection. The fact that "inexpensive" and "pleasant association" were non-technical concepts which as such did not count for inventive step, did not matter for the question of clarity.

In T 586/97 the main claim was directed to an aerosol composition comprising a propellant and an active ingredient which was not defined. The board held that, when an essential ingredient comprised in a chemical composition is open to be labelled arbitrarily "active ingredient" or not, the meaning of that feature would be variable. Leaving the public in doubt as to which compositions are covered by the claim would be at variance with the principle of legal certainty. Therefore, the claim at issue failed to meet the requirement of clarity imposed by Art. 84 EPC 1973. See also T 642/05, T 134/10.

In decisions T 1129/97 (OJ 2001, 273) and T 274/98 the board emphasised that, to satisfy the clarity requirement, the group of compounds/ingredients according to the claim had to be defined in such a way that the skilled person could clearly distinguish compounds/ingredients that belonged to the claimed group from those that did not (see also T 425/98 regarding the expression "consisting of a major amount of").

In T 268/13 the board concluded that a claim to a "method for producing a [...] decorative strip having a [...] structure consisting of a text or graphic symbol [...]" satisfied the requirements of Art. 84 EPC 1973. Although it was impossible to give an entirely general, universally applicable definition of what constituted a symbol, in the case in hand it would be clear whether or not a particular character was a symbol in the given cultural, linguistic or technical context. The claim therefore presented neither somebody wanting to avoid infringing the patent nor a court deciding on infringement with an impossible task.

In T 1845/11 the board concluded that the term "Asian race" was not clear. Clearly defined objective criteria for patient assignment into racial groups were not available to the skilled person.

In T 860/93 (OJ 1995, 47) the board decided as follows: where a quality is expressed in a claim as being within a given numerical range, the method for measuring that quality must be general technical knowledge, so that no explicit description is needed, or a method of measuring that quality needs to be identified (decision T 124/85 followed). In contrast, where a claim specifies a relative quality, in this case that the products should be "water-soluble", it is not normally necessary to identify any method for its determination (for the term "soluble" see also T 785/92, T 939/98, T 125/15). In the following cases the boards confirmed that the use of a relative term in a claim may be accepted where the skilled person is able to understand the meaning of this term in a given context: T 860/95 ("for a long period of time"), T 649/97 ("transparent"), T 1041/98 ("thin plate"), T 193/01 ("thin film"), T 545/01 ("flat"), T 378/02 ("smooth"), T 2367/16 ("overnight") and T 2402/17 (relationship between the terms "higher" and "lower oscillation susceptibility" and "smaller values"). In T 1045/92 the claims concerned "a two-pack type curable composition comprising [...]". In the board's view "a two-pack curable composition" was an item of commerce as familiar to readers skilled in the polymer art as everyday articles were to the public at large. The claim was therefore clear.

In T 1170/16 it was held that "useful for" in the expression "a liquid absorbent structure useful for absorbent articles" of claim 1 resulted in a lack of clarity. "Useful for" included an element of value with respect to the features it linked. In claim 1 this benefit was not defined and so the reader was left in the dark as to how the structure was useful for the absorbent articles. The board did not accept that "useful for" was synonymous with "for", meaning "suitable for". It had an effect going beyond mere suitability. In T 1526/22 the examining division had objected to the wording [apparatus] "for a motor vehicle driver assistance for an ego vehicle" in the claim because this suggested that an effect supporting motor vehicle assistance was to be produced, which was however not apparent from the wording of the claim. The board interpreted the wording of claim 1 as meaning an apparatus suitable for a motor vehicle driver assistance system for an ego vehicle, as is usual for a purpose feature in an apparatus claim in the form "apparatus for ...". Claim 1 did not require the claimed apparatus to be configured to provide the output of the state estimator as input to a driver assistance system. The board did not see a lack of clarity in that respect.

In T 651/05 the board found that the introduction of vague terms created a lack of clarity due to different but equally valid interpretations (see also T 621/03, T 127/04). In T 1534/10 a claim contained the feature "that the data carrier (1) is constructed in a multi-layered manner as a laminate and contains at least two films (4, 5) which are integrated as a cover film (4) or as a core film (5) into the layer construction of the laminated data carrier". The board considered this wording ambiguous because it combined a plural form ("at least two films (4, 5)") with a singular form ("as a cover film (4) or as a core film (5)"), making it unclear whether the "at least two films" were each either a cover film or a core film, or whether together they formed a new film that was then either a cover film or a core film.

Where, on one of several possible constructions of a vaguely formulated claim, part of the subject-matter claimed is not sufficiently described to be carried out, the claim is open to objection under Art. 100(b) EPC 1973 (T 1404/05, see also chapter II.C.8.1. "Article 83 EPC and support from the description").

In T 1065/18 the board held that due to its wording ("Pharmaceutical composition ... packed or filled into a container"), the claim put the emphasis on a pharmaceutical composition rather than a container comprising said composition. This made it unclear whether the protection sought was limited to the pharmaceutical composition per se, or whether a container comprising a pharmaceutical composition was to be protected (see T 352/04 for a similar case). Thus, the claim lacked clarity.