Intermediate generalisations – a review

G. Murnane (GB), European Patent AttorneyG. Murnane (GB), European Patent Attorney, Murgitroyd & Company

Part of the skill set required by a patent attorney is the ability to generalise. Most patent claims are in themselves generalisations from one or more particular examples. When a patent attorney is instructed to draft a new patent application, he or she will often have been provided with one or more embodiments of an invention. There will have been an explanation of the advantages that the invention offers, and the problems it solves, but it is very rare that the inventor will have had an opportunity to develop every possible way of carrying out the invention. It is left to the patent attorney, not only to describe the particular embodiments that the inventor has devised, but also to generalise the invention in the language of the claims, taking into account the prior art known at the time, so that the patent application gives the applicant a fair scope of protection which is not just limited to one or two specific embodiments.

However, after filing of the patent application and during prosecution of the application at the European Patent Office, generalisation becomes more problematic. When faced with new prior art objections, the attorney may seek to amend the patent claims, looking for amendments to the claims which balance the need to provide a useful scope of protection for the applicant with the requirement to distinguish the claimed invention over the cited prior art. It is when using the description as a source for claim amendments that the risk is greatest of coming up against the dreaded term "intermediate generalisation".

It may feel as if intermediate generalisations have been with us forever. However they are a relatively new phenomenon. The first mention of the term in a Board of Appeal decision was in 1992, in T 0551/90, and the expression was used only by the appellants making an added subject matter objection against an amended claim in opposition proceedings. The Board stated:"The Appellants ... argue in effect that the relevant features incorporated into the claim are an arbitrary selection among those possible so that an unallowable intermediate generalisation has been made. In particular, they say that the claimed disposition of the conduits has only been disclosed in combination with an impeller which has an axial extent twice that normally used ..." The Board was satisfied that there was no strict requirement for the impeller to be of any particular axial extent, and allowed the amendment.

In T 0415/91 of 13 May 1992 the Board themselves introduced the term to describe an amendment in which there was an omission from Claim 1 of the original limitation to three-phase AC: "The expression "three-phase" appears about 200 times in the application as originally filed and no other number of phases is mentioned at all. There is no suggestion that the described number of phases, three, is by way of example. The opening sentence of the description states: "The invention herein relates to a high DC voltage power supply adapted for incorporation within a motor vehicle electrical circuit of the low DC voltage type." This statement is too general to permit the deduction of an intermediate generalisation in respect of the number of phases." What is interesting here is that the Board did not state that intermediate generalisations should not be permitted, but simply argued that one particular sentence was not sufficient to permit the particular intermediate generalisation.

There was one more decision from 1992 referring to an "intermediate generalisation" in T 0118/91 of 28 July 1992, and again the term was introduced by the unsuccessful appellant.

Three such decisions followed in 1994, and one in 1995, and then silence until 1999, when there were a handful of decisions referring to intermediate generalisations in that year and the following years.

The first edition of "Case Law of the Boards of Appeal of the European Patent Office" which referred to "intermediate generalisations was the 2006 edition. The term "intermediate generalisation" appeared in a discussion of T 962/98 in a section headed ""Tests" for the assessing allowability of an amendment": "The board did not rule out the possibility that there might be situations where some characteristics taken from a working example could be combined with other features disclosed in a more general context without necessarily creating an objectionable intermediate generalisation. However, under Art. 123(2) EPC, such an intermediate generalisation was admissible only if the skilled person could recognise without any doubt from the application as filed that those characteristics were not closely related to the other characteristics of the working example and applied directly and unambiguously to the more general context. In other words, in order to be acceptable, this intermediate generalisation had to be the result of unambiguous information that a skilled person would draw from a review of the example and the content of the application as filed."

In the 2010 edition of "Case Law of the Boards of Appeal of the European Patent Office" there was a complete section entitled "Intermediate generalisation - non-disclosed combinations". This marks the appearance of the term "intermediate generalisation" in the mainstream of patent examination terminology. According to the text of the 2020 edition, the decision T 1067/97 confirms that "According to established jurisprudence of the boards of appeal, if a claim is to be restricted to a preferred embodiment, it is normally not admissible under Article 123(2) EPC to extract isolated features from a set of features which have originally been disclosed in combination for that embodiment. Such kind of amendment would only be justified in the absence of any clearly recognisable functional or structural relationship among said features". However this decision does not itself use the term "intermediate generalisation".

The term "intermediate generalisation" did not appear in the "Guidelines for Examination in the European Patent Office" until the 2012 edition, when the Guidelines were extensively rewritten and a section entitled "Intermediate generalisations" appeared at point 3.2.1 of Part H, Chapter V "Allowability of amendments - examples". The section referred to five examples, based on five Board of Appeal decisions - T 300/06, T 461/05, T 1164/04, T 200/04 and T 166/04.

The example of T 461/05 disappeared in the 2017 version of the Guidelines, but the other four examples are still there in the 2022 version. T 461/05 described an allowable intermediate generalisation in which an original independent claim 1 was limited by adding only some features of a specific embodiment disclosed in the application as originally filed. According to the example in the Guidelines: "This was defined by the Board using the term "intermediate generalisation" or "intermediate restriction". The Board held that omitting features of an embodiment would introduce new information if these features are necessary for carrying out this embodiment. In the present case, the omitted features were considered to have their own recognisable function independent from the functioning of the rest of the system. Since they were neither presented as essential in the original application nor recognised as essential by the skilled person to carry out the invention, the Board considered that the requirements of Art. 123(2) were met."

The four remaining examples in the Guidelines can be summarised as follows:

Example 1 (T 300/06) - a specific embodiment could be read in conjunction with a broader statement elsewhere in the description, so the intermediate generalisation was allowed.

"The amended claim relates to a heddle for the harness of a loom. The original claim was limited by introducing features that were disclosed only in connection with a specific embodiment in which the eyelet of the heddle had the shape of a spindle. This shape was not included in the amended claim. In the general part of the description it was also mentioned that the eyelet could also have other shapes such as an elliptic shape. Therefore the board concluded that the amendment was allowable under Art. 123(2)."

Example 2 (T 1164/04) - a feature derived from a specific embodiment was only disclosed in conjunction with other, unclaimed features, so the amendment was not allowed.

"Claim 1 relates to a water dispersible and flushable absorbent article. Amended claim 1 specifies that each of the first and second fibrous assemblies is a wet laid tissue. The application as filed referred, in connection with the first fibrous assembly, to a wet laid tissue in combination with other features (tissue is apertured; tissue is provided with fibrils or sufficient inherent porosity). Since the first fibrous assembly is disclosed in the application as filed as being a wet laid tissue only in combination with other features which are not present in claim 1, the amendments made constitute a generalisation of the originally disclosed technical information and thereby introduce subject-matter extending beyond the content of the application as filed."

Example 3 (T 200/04) - a new independent method claim was introduced in opposition proceedings, while the original application only had composition claims; the amended claim was considered to be a generalisation of the example methods and not allowed.

"Original claim 1 relates to a coating composition comprising at least one rosin compound, at least one polymer and an antifoulant. After amendment a new claim was introduced relating to a method for preparing a coating composition comprising the mixing of at least one rosin compound, at least one polymer and an antifoulant. The only basis for the method is the examples. The board observed that for some solutions the amount of added rosin was extremely low whereas for others it was extremely high. The subject-matter of the amended claim was considered to be an unallowable generalisation of the examples, since nothing in the description indicated to the person skilled in the art that the observed variations were not essential to make a coating composition."

Example 4 (T 166/04) - a feature of an overall disclosure described as being essential was omitted from an amendment, so the amended claim was not allowed.

"Original claim 1 relates to a multi-processing system comprising a shared memory, a directory and a serialisation point. The serialisation point is defined in functional terms. Claim 1 was amended by adding features that were addressed in the description as part of the cache coherence strategy. The board held that the incorporated features, albeit disclosed as such, had been isolated in an arbitrary manner from the overall disclosure of the cache coherent memory access architecture. At least one feature had been omitted although its function was presented as being essential to achieving cache coherence. Therefore amended claim 1 was not directly and unambiguously derivable from the original application (T 166/04)."

After the removal of the allowable amendment referred to in T 461/05, there remains only one example of an allowed amendment in the Guidelines, along with three examples of amendments which were not allowed. This suggests that arguing for the allowability of an amendment may be difficult. However, when looking closer at the examples, one should not be deterred from arguing for allowability. Example 4 concerns an unusual case in which an amendment omitted a feature whose function had been described as "essential". This is not normally the case in situations where intermediate generalisations are under discussion. Example 3 concerns an even more unusual case in which a new category of claim (a method for preparing a coating composition) was introduced in opposition proceedings, when the original application and granted patent had only included product claims (a coating composition). There are very few cases where method claims are introduced in opposition when the application and granted patent had no method claims.
The example of an unallowable intermediate generalisation that appears to have most relevance is Example 2, which refers to T 1164/04. This case concerned a water dispersible and flushable absorbent article comprising a liquid pervious topsheet comprising a first fibrous assembly, a liquid impervious backsheet comprising a second fibrous assembly and disposed beneath the topsheet, and an absorbent core disposed between the topsheet and the backsheet. The patentee filed an amended claim 1 as part of a first auxiliary request, which differed from claim 1 as granted in that it defined that each of the first and second fibrous assemblies is a wet laid tissue.

Claim 1 as filed included two optional features:

"said first fibrous assembly more preferably also comprising an apertured wet laid tissue"; and

"said second fibrous assembly preferably comprising a wet laid tissue".

The Board held that the second feature provided a basis for the fibrous assembly of the backsheet being a wet laid tissue, but the first feature did not support the fibrous assembly of the topsheet being a wet laid tissue without further defining the wet laid tissue as "apertured".

The application as filed described that the topsheet "may be manufactured from a wide range of materials such as air laid, wet laid, or carded nonwoven materials". However the Board referred to this as a "general reference" which could not be regarded as a specific disclosure of wet laid tissues.

The Board stated: "Although the application as filed discloses that the second fibrous assembly may be a wet laid tissue (see in particular original claim 1), there is no clear and unambiguous disclosure of the first fibrous assembly being, generally, a wet laid tissue. Indeed, the application as filed consistently refers, in connection with the first fibrous assembly, to a wet laid tissue in combination with the feature that the tissue is apertured (see original claim 1), or with the feature that the tissue is provided with fibrils (see original claim 14) or sufficient inherent porosity (see page 21, lines 1 to 25)."

In fact there was an illustrated embodiment in Fig. 7 of a top sheet without apertures. The description stated: "As depicted in Figure 7, the fibrous assembly 52 does not include discrete apertures such as apertures 50 depicted in Figures 5 and 6. However, in order to maintain fluid transmission capabilities sufficient to enable their use in absorbent articles, such webs include sufficient inherent porosity." The fibrous assembly 52 had been described earlier, with reference to Figs. 5 and 6, as a wet laid tissue. Hence the skilled person reading the description would understand that apertures are not essential in the wet laid tissue of the top sheet, as long as the web has sufficient inherent porosity. The actual porosity required is not described in the application, and the skilled person would understand that this is a subjective property of the web; in other words the web must be sufficiently porous to provide comfort to the wearer. In fact elsewhere in claim 1 it is recited that the top sheet is liquid pervious.

Hence if the skilled person reads the complete disclosure carefully, he would understand that the first fibrous assembly of the topsheet may be "wet laid" from the general statement in the description that the topsheet "may be manufactured from a wide range of materials such as air laid, wet laid, or carded nonwoven materials", and that it may be a "wet laid tissue" without apertures from Fig. 7 and the associated description, as long as it "sufficiently porous". In any case claim 1 recites that the top sheet is liquid pervious.

This seems to be a fair basis for claiming a topsheet comprising a first fibrous assembly which is a wet laid tissue. The important test is whether the skilled person is presented by the amendment with information which is not directly and unambiguously derivable from the originally filed application. It is difficult to see how the idea of the fibrous assembly of the topsheet being a wet laid tissue, without defining whether the tissue is apertured or not, could be considered as new information, when the application as originally filed disclosed a topsheet of wet laid tissue with and without apertures.

Study of the "intermediate generalisation" examples in the Guidelines leads to the conclusion that we should not take the fact that an amendment can be characterised as an "intermediate generalisation" as simply meaning that the amendment is not allowable under Art. 123(2) EPC. The "intermediate generalisation" tests that have been developed in the case law of the Boards of Appeal are not simple yes/no tests. Instead we should look at what the application as a whole teaches the skilled person.

While in an ideal world every possible claim amendment would be derivable directly from a claim forming part of an exhaustive and complete set of dependent claims, covering every alternative thought of by the inventor and the drafter of the patent specification, such an ideal world does not exist. In practice the constraints of claim fees mean that the applicant will continue to have to look to the description for distinguishing features when faced with prior art of which they were not aware at the time of filing.

As a final thought, it would be helpful to redress the balance in the "intermediate generalisation" examples in the Guidelines as well, so that there are equal numbers of allowable and non-allowable amendments in the examples.