The Problem and Solution Approach – Basic Case Law and Recent Development (I)

M. M. Fischer (DE), European Patent Attorney

Part 1
This is the first part of an article that is based on a talk held by the author on September 8, 2015 at the European Patent Experts’ Forum (EuPEX) in Munich. The author thanks the audience for the animated discussion accompanying the talk. Some of the contributions have been woven into the article. The second part of this article will be published in epi Information 4/2016.

What the Lord’s Prayer is to Christians all over the world, is the problem and solution approach to European Patent Attorneys. You pray it whenever it comes to the assessment of inventive step – before the Examining Division, the Opposition Division or the Board of Appeal – in hope that your prayer will be answered and a patent will be granted. While it cannot be proven that the Lord’s Prayer is God’s favourite prayer, there cannot be any doubt that the problem and solution approach is the EPO’s favourite prayer. And what is more, it is the one and only that will be answered. This should be reasons enough to know as much as possible about this approach. Although the problem and solution approach is very well established case law of the Boards of Appeal, there has been a development in the understanding of the term “closest prior art” which has now found its way into the latest version of the Guidelines for Examination in the European Patent Office (GL). While the Guidelines give some advice on how to apply the problem and solution approach, some more examples from the case law may be helpful to add some flesh to the bones in order to fully elucidate the approach. The purpose of this article is to give an introduction into the concept of the problem and solution approach in its basic version by supplementing the corresponding passages in the Guidelines with recent decisions of the Boards of Appeal and the author’s personal thoughts. This article does not cover the treatment of a mix of technical and non-technical features, partial problems, problem inventions and secondary indicia.

The EPO assesses the presence of an inventive step (Art. 56 EPC) using the problem and solution approach. Although the problem and solution approach does not have a direct basis in the EPC, it can be derived from R. 42(1) (c) EPC which stipulates that the invention must be disclosed in terms of a technical problem and its solution[1]. The Guidelines state under G-VII, 5 that in order to assess inventive step in an objective and predictable manner, the so-called "problem and solution approach" should be applied. Thus deviation from this approach should be exceptional. In the problem and solution approach, there are three main stages:

  • determining the "closest prior art",
  • establishing the "objective technical problem" to be solved, and
  • considering whether or not the claimed invention, starting from the closest prior art and the objective technical problem, would have been obvious to the skilled person.

A. Closest Prior Art

Turning to the identification of the closest prior art first, the main criteria for selecting the closest prior art document[2] are that the closest prior art:

  • should have a same or similar purpose or effect as the invention or
  • should deal with a similar technical problem as the invention or at least belong to the same or a closely related technical field as the claimed invention or
  • should have a similar use and require minimal structural modifications.

It has always been emphasized that the number of features that the claim has in common with the prior art is by itself not a suitable criterion for selecting the closest prior art. Although the criteria above are based on well-established case law, it still seems to be a constant source of dispute as more recent decisions show.

A lot of effort was invested in the past to show that one document is the (one and only) closest prior art document, while other documents may have been prematurely disregarded as closest prior art documents[3]. This practice is probably also due to the superlative expression “closest prior art”. Fortunately, in response to some recent decisions of the EPO, also section G-VII, 5.1 of the Guidelines has been updated such that it now explains that in some cases there are several equally valid starting points for the assessment of inventive step, e.g. if the skilled person has a choice of several workable solutions, i.e. solutions starting from different documents, which might lead to the invention. The requirement of inventive step is negatively defined in the EPC. Pursuant to Art. 56 EPC, an invention shall be considered as involving an inventive step if, having regard to the state of the art, it is not obvious to a person skilled in the art. That means that it cannot be shown directly that the subject-matter of a claim invention involves an inventive step. Rather, if the subject-matter of a claim can be derived from the state of the art in an obvious manner, it can be concluded that it does not involve an inventive step; in all other cases, it involves an inventive step. The problem and solution approach allows to construct a logical chain of arguments (or “convincing chain of considerations”) to demonstrate that the subject-matter of a claim can be derived from the state of the art in an obvious way. If such a logical chain of arguments cannot be built, the subject-matter of the claim involves an inventive step.

As a consequence, in order to show that the subject-matter of a claim involves an inventive step, it may be necessary to apply the problem and solution approach to each of these starting points in turn, i.e. in respect of all these workable solutions. In order to show that the subject-matter of a claim does not involve an inventive step, it is sufficient to show starting from one appropriate starting point using the problem-and-solution approach that it was obvious for the skilled person to arrive at the claimed subject-matter[4]. The Guidelines come to the conclusion that the only relevant question is whether the document used is an appropriate/feasible starting point for assessing inventive step.

Hence, any document that fulfills one or more of the criteria mentioned above may qualify as an appropriate starting point. Instead of thinking of the selection of the closest prior art as the one and only document, one should think of this step in terms of a (pre-)selection of a set of documents from which the skilled person could have realistically started to arrive at the subject-matter of the claim in an obvious way. In other words, only those starting points (documents) are considered from which the skilled person had a reasonable chance to arrive at the subject-matter of the claim in an obvious manner[5]. If it cannot be shown from these appropriate starting point documents that the subject-matter of the claim is obvious, then it can be shown even less that the subject-matter of the claim can be arrived at in an obvious way starting from any other (inappropriate) starting point which leads to the conclusion that the subject-matter of the claim is inventive.

In T 967/97 the Board stated that the problem and solution approach was essentially based on actual knowledge of technical problems and ways to solve them technically that the skilled person would, at the priority date, be expected to possess objectively, i.e. without being aware of the patent application and the invention that it concerned. If the skilled person had a choice of several workable solutions that might suggest the invention, the rationale of the problem and solution approach required that the invention be assessed relative to all these possible solutions before any decision confirming inventive step was taken. To deny inventive step, no special grounds had to be given for a pre-selection of prior-art citations, even if several workable solutions were available to the skilled person; the reasoning on inventive step merely served to show that the invention was obvious to the skilled person from the prior art in relation to (at least) one of these solutions (see also T 558/00, T 970/00, T 172/03, T 323/03, T 21/08, T 308/09, T 1289/09).

The following table[6] provides an exemplary overview over how the Boards of Appeal have applied the main criteria above (and other criteria) in various cases to qualify documents as appropriate starting points:

Decision Claim Appropriate starting point Inappropriate starting point Remark
T 570/91 “1. A piston for an internal combustion engine...” Piston for internal combustion engines Piston for a compressor Same purpose (genericallythe same)
T 817/94 "1. An electrically operated hand mixer for processing food…” Electrically operated hand mixer Stand mixer Similar use and requires minimal structural modifications. In contrast to the stand mixer, in the hand mixer, the drive unit and the mixing tool are in a right angle.
T 487/95 “1. Military protective helmet comprising a calotte resistive against gunfire…” Military protective helmet A worker’s safety helmet. This document also forms part of the knowledge of the person skilled in the art and can be used as a document in which the skilled practitioner could find a solution to an objective technical problem, see also T 149/00. Same purpose (generically the same)
T 870/96 "1. An image projection apparatus comprising an information display system having at least one display panel [typically a LCD panel] with a rectangular surface for generating images to be projected,…” Image projection apparatus having an LCD panel with a rectangular surface for generating images to be projected. It also relates to problem of increasing the brightness and uniformity of the illumination system associated with said display panel. Lenticulated collimating condensing system. It does not relate to LCD projection. Examining Division chose inappropriate CPA, possibly based on number of common features.
T 66/97 "1. A method of connecting a pair of hermetic optical fibers having an electrically conductive hermetic layer coated on optical fiber glass,…” A method of connecting hermetic optical fibres by an aerial discharge. It also relates to the problem of reduced break strength arising in this context due to the interference of the hermetic layer with the fusion process. It has no reference to hermetic optical fibres and, not surprisingly, to any fusion problems caused by the presence of hermetic layers. Examining Division chose an inappropriate CPA, which cannot be considered as a technically realistic starting point.
T 513/00 <Automatic coffee maker that has one brew chamber for coffee alone or together with milk for cappuccino.> No appropriate starting point available. The available prior art documents do not show any piece of prior art from which the subject-matter of claim 1 could be obtained in an obvious manner. D1 refers to known coffee machines which require a human being for the preparation of cappuccino. D1 shows a coffee maker which has a first station for the delivery of coffee and a second station for the delivery of milk foam. A human being has to move a cup from the first station to the second station. The problem indicated in the patent and the original patent application refers to a difficulty that arises with an automatic coffee maker that has one station for the delivery of either coffee or cappuccino. It makes sense that the skilled person starts from a coffee maker for which this difficulty exists. Since this difficulty does not exist with a coffee maker as disclosed in D1, such a coffee maker represents an artificial rather than a realistic starting point. See also T 835/00 which says that if a relevant problem is not derivable, the measures for its solution are a fortiori not derivable. In other words, the invention is not obvious in the light of such art.
T 211/01 "1. A process for preparing a halogen-free hydroxy- polyalkene amine composition…." The most suitable starting point is the prior art process mentioned in the patent in suit on page 2, lines 25 to 29, from which the same products were obtainable as in the patent in suit via imination of an ozonolysis product of a polyolefin and final hydrogenation of the imine. Evidence was provided that D5 did not furnish any amination reaction at all but merely an inhomogeneous mixture of starting materials. Since this evidence was not contested by the Appellants, the Board concludes that D5 is obviously defective as would be readily recognised by those skilled in the art when trying to reproduce its disclosure. A document which is obviously defective as would be readily recognised by those skilled in the art when trying to reproduce its disclosure cannot be taken as the most promising and appropriate starting point for the assessment of inventive step. Quite apart from the fact that a skilled person would normally not consider an obviously defective disclosure at all, the Board deems it in particular artificial to select such defective disclosure as a starting point for evaluating inventive step, when there exists other prior art which is not doubted with regard to its disclosure but is also directed to the same purpose or effect as the patent in suit.
T 1228/08 "1. Apparatus for processing a signal comprising: <features relating to hierarchical coding but not to multicasting>” In this music-on-demand system, a server stores various compressed versions of a musical piece, each version corresponding to a different connection speed between the server and the client and consequently to a different quality. In delivering the music to a client, the appropriate version is packetized and communicated through a packet-switched network. It discloses the use of hierarchical coding, which is indeed a major aspect of the present, but in the context of multicasting. A conscious choice of starting point not only determines the subjectmatter serving as a starting point but also defines the framework for further development. Thus, using D1 as a starting point would mean that any further development would be carried out in the context of multicasting: it is unrealistic to suggest that, starting from this disclosure, the skilled person would go outside this framework - indeed take a technical step back - to develop a non-multicasting system (see also T 439/92).
T 56/09 "1. A syringe by which medicine may be apportioned in preset doses from an ampoule…” A syringe by which medicine may be apportioned in preset doses from an ampoule. The syringe disclosed in D6 is not of the same type as that claimed, since it is not a syringe by which medicine may be apportioned in set doses from an ampoule, and as already mentioned above it has fewer features in common with the subject- matter of claim 1 than D1. Different type of syringe cannot be appropriate starting point. [To make the case even more vivid and memorable: A fire brigade syringe can never be an appropriate starting point prior art for a medical syringe regardless how many features they have in common.]
T 1764/09 “A variable focus lens (2, 26) being adapted for a contact lens or an intraocular lens comprising a transparent rear wall (8, 28), a transparent front wall (6, 106) having a convex curved surface (10) and a concave inner surface (19), a cavity (14, 114) formed between the transparent front wall and the transparent rear wall, first and second immiscible fluids (16, 17) of differing refractive index contained within said cavity, and electrodes (18, 21) to which a voltage is able to be applied to change the curvature of a fluid meniscus (4, 104) between the two fluids, wherein at least the rear wall of the lens includes a biocompatible material, which material provides for biocompatibility of the lens with the eye and a periphery of the front wall joins a periphery of the rear wall to form an acute internal angle (alpha) at their joining region (J)." The invention generally relates to a lens adapted for a contact lens or an intraocular lens. Its focal length can be varied by controlling the voltage applied to electrodes so as to change the curvature of a fluid meniscus between two immiscible fluids, based on the physical phenomenon of electro-wetting. No prior art is available disclosing the use of electro- wetting in such a lens. (Possibly a pioneering invention.) D1 is no more than a speculative review of what might be potentially feasible in the future. No concrete realisation of a fully adapted lens for a contact or intraocular lens was described in D1. Speculative document not suitable as appropriate starting point (similar to T 211/01)
T 535/107[7] "A mirror (1) comprising a first transparent glass plate (4) at least partly provided on the rear side with a reflecting coating (2) as well as at least one integrated electrical means (6), wherein the first glass plate (4) comprises transparent and/or half-reflecting portions (8), the first glass plate (4) is bonded to a second glass plate (10) with the aid of a transparent adhesive layer (12) in the form of a laminated glass pane, and electrical means (6) are mounted on an electrically conducting coating (14) of the second glass plate (10) in portions opposite the transparent and/or half-reflecting portions (8) of the first glass plate (4).” Although not explicitly mentioned in the claim (but implicit by the features), the claim is directed to a mirror for use in a damp room. D1 shows a mirror for use in a damp room. The mirror shown in D13 is an interior rear-view mirror for a vehicle and not appropriate for use in damp rooms. Appellant has explained that the skilled person would proceed in this way in order to make the mirror [of D13] suitable for use in a damp room. However, this argument cannot be endorsed. There is no reason to make an interior rearview mirror suitable for use in a damp room. This would lead to rebuilding said mirror for a completely different use. Such a way of proceeding cannot be obvious. Although the skilled person is completely free in the choice of a starting point, he is later bound by this choice. If a skilled person choses a specific interior rear-view mirror for a car as starting point, he can pursue its development, but the normal outcome of this development will in the end still be a rear-view mirror for a car and not a mirror suitable for use in a damp room (see T 570/91 [4.4]). A conscious choice, i.e. a choice made in full awareness of the advantages and drawbacks of the different types, not only determines the subject- matter serving as starting point but also the framework of the development, i.e. a development within this type. In the course of the development a change from the consciously chosen type to another, which was known before but which had not been chosen, is unlikely and, as a rule, not obvious (T 817/94).
T 698/10 "A method for video processing, the method comprising: decoding an AVS bitstream based on decoding version information within said AVS bitstream, wherein said decoding version information was inserted in said AVS bitstream into a sequence user data (206) after a sequence header (204) of the AVS bitstream during coding of said AVS bitstream, wherein decoding comprises mapping of the sequence user data (206) to a decoding version ID via a AVS decoding list." D1 is an article describing the main technical features of the AVS standard for coding and decoding video signals. The AVS standard is described in the present application as the starting point for the invention (see paragraphs [0002] to [0006] of the application as filed). D1 thus belongs to the same technical field as the claimed invention, i.e. the coding and decoding of video signals according to the AVS standard. It also serves a similar purpose and implicitly or explicitly addresses similar or the same technical problems as the claimed invention, i.e. those solved by the use of the AVS standard, such as a highly efficient video coding/decoding and an optimisation between absolute coding performance and complexity of implementation (see the INTRODUCTION section on the first page of D1). Moreover, the video processing method disclosed in D1 has several technical features in common with the method of claim 1, these features being essentially implied by the reference to the AVS standard in claim 1. According to the appellant, no available prior art document is an appropriate starting point. The appellant disputed that D1 could be regarded as the closest prior art, because it did not disclose the problem arising from the existence of different versions of the AVS standard. The Board concurs with the appellant that D1 does not disclose this further problem, but disagrees that it should disqualify D1 as starting point for the assessment of inventive step. Indeed, the closest prior art need not disclose all the problems solved by the claimed invention, in particular it need not disclose the objective technical problem, which is only determined in the second step of the problem and solution approach based on the technical effect(s) provided by those features distinguishing the invention as claimed from the closest prior art. In the present case, there is no other prior art on file which discloses the objective technical problem or which would qualify better than D1 as the closest prior art. During the oral proceedings, when asked by the Board which prior art was the closest prior art if not D1, the appellant replied that there was none. The Board cannot agree with this view. According to Article 56 EPC an invention is to be considered to involve an inventive step if, "having regard to the state of the art", it is not obvious to the skilled person. Hence, the assessment of inventive step has to be based on an evaluation of the invention in view of the prior art. The expression "closest prior art" also does not mean that it must be sufficiently close to the claimed invention on an absolute basis, but only that it must be relatively closer to the claimed invention than the other prior-art disclosures, i.e. it is selected as the most promising starting point - or the most promising springboard towards the invention.
T 2255/10 "1. A production method for silicon wafers, comprising:...” D1 discloses a method by which vacancies are injected into a silicon wafer. Moreover, the method of document D1 has many technical features in common with the claimed invention. The Board therefore considers that document D1 is a perfectly suitable choice as closest prior art for the main request. The appellant stresses the aspect of providing a high density of oxygen precipitates (BMDs). The Board accepts that this aim is mentioned in the application, the invention being described, for example, as providing a "high quality silicon wafer having a DZ layer, which is suitable for forming a device, as the surface layer, and also having a high BMD density area having a proximity gettering effect". The appellant concludes that document D1 is not a suitable choice of closest prior art, as the purpose of the method disclosed in this document is different, namely to control the distribution of dopant elements in the silicon wafer, thereby controlling resistivity. The Board holds that it cannot be legitimately asserted that the purpose of the invention as claimed is to provide a silicon wafer having BMD layer with high density, or for that matter having a denuded zone. In establishing the closest prior art, the determination of the purpose of the invention is not to be made on the basis of a subjective selection from among statements of purpose which may be set out in the description of the application, without any reference to the invention as defined in the claims. On the contrary, the question to be asked is, what, in the light of the application as a whole, would be achieved by the invention as claimed. The applicant cannot influence the selection of the closest prior art by adding purposes into the application that are not achieved by the invention.
T 386/11 "1. "An apparatus for conveying slaughtered animals, in particular birds or parts of birds, which apparatus comprises …, and wherein along the conveyor's path there is at least one guide member provided which is capable, after the carrier is rotated to a predetermined position, of moving the animal suspended from the carrier such that it is diverted around the processing station, characterized in that..." It discloses an apparatus comprising carriers that can rotate the transported birds over 90° but that do not divert them around a processing station, which is a central aspect of the present patent. It discloses an apparatus for conveying slaughtered birds, comprising a plurality of carriers for the birds which travel a path passing at least one processing station and which is also capable of moving the bird suspended from the carrier such that it is diverted around the processing station. Not only features at the beginning of the claim which often define the “main object” of the claim are important. If, for instance, for whatever reason it may be, a person skilled in the art prefers and decides to start from a specific apparatus for rotating the transported birds over a quarter turn, he can further develop that apparatus, but at the end of that development the normal result will still be an apparatus for rotating the transported birds over a quarter turn and not an apparatus for diverting the transported birds around a processing station.
T 749/11 "1. Steam cooker for warming up food at ambient pressure… <steam is led from the steam generator into a heating chamber>“ Standard oven (does not work with steam). A standard oven is basically not arranged to heat food using steam. It belongs to another type and is not a steam cooker. Even if a bowl filled with water were in the heating chamber, the standard oven cannot be considered as a steam cooker. Furthermore, the steam would not be led into the heating chamber, as claimed, since it would develop in the heating chamber itself. Steam cooker Same type (generically the same)

In the determination of an appropriate starting point, not all features of the claim have the same weight. While some features define the type/genus of the subject-matter, other features are less important. In apparatus claims, the claims start with the term defining the “main subject-matter”, e.g. “A lawn mower, comprising…”. These first words of a claim typically define what the subject-matter of the claim is all about and also contain inherent features (e.g. four wheels, engine, blades, etc.). The first words of a claim are often an important indicator for documents which qualify as appropriate starting point. However, also other features which define the type of the main subject-matter should be disclosed in the appropriate starting point. Indications of purpose (“Apparatus for cooking…”) are important. An appropriate starting point should/must be designed for the same purpose. The purpose of an apparatus does not have to be mentioned explicitly but can also be implicitly derived by the features it contains. Moreover, the term “type” or “genus” is intimately related to the term “purpose” in the sense that things that belong to the same type/genus also have the same purpose. In particular if a prior art item accidentally anticipates all the features of a claim, it often occurs that a small clarification of the claim renders the subject-matter of the claim novel and at the same time diverts the subject-matter of the claim so far from the prior art item that it disqualifies as closest prior art.

Also the constituent material (main material) of the subject-matter of the claim can be an indicator for a closest prior art document[6]. It can be derived, for instance, from T 1228/08 that the skilled person would not make any step back (undo any steps that are substantial for the appropriate starting point). For example, if the invention concerns a “tool made from metal”, it would not make any sense for the skilled person to start with a “tool made from wood” because it would be of no use to him in the sense of a realistic further development. As will be discussed below, it is often impossible in such cases to formulate a problem without giving a hint to the solution. Moreover, a claim dependent on an independent claim may have a different closest prior art item since e.g. a feature in the dependent claim may change the constituent material such that a closest prior art item for the independent claim may disqualify as the closest prior art item for the dependent claim.

A document that the applicant mentions himself in the background section of the application but which is only an “internal prior art” that has not become public before the priority date of the application cannot be used for the assessment of inventive step (T 211/06).

One may be inclined to think that a first document is better starting point than a second document since the first document already contains the features relating to what is subjectively considered to be the “gist”, “core” or “knack” of the invention. This, however, may be a misconception since the skilled person may well be able to transfer the teaching relating to this “knack” of the invention from a teaching relating to the same, broader or neighboring technical field. As explained above, it is more important to select a generically similar or identical document as appropriate starting point.

Regarding the criterion “similarity of the problem”, it should be mentioned that this criterion appears to be more problematic than the criterion of the same or similar purpose. The reason is that it is not quite clear which problems are to be compared. Since the selection of one or more appropriate starting points is made to determine the objective technical problem, it cannot be the objective technical problem. Hence, one can only compare the subjective technical problem of the potential appropriate starting point with the subjective technical problem of the claimed invention. However, while a purpose can be attributed to any subject-matter disclosed in a prior art document, a problem cannot always be attributed. The reason is that a purpose is an absolute criterion while a problem is a relative criterion. In particular non-patent prior art documents do not always mention a (subjective) problem. The situation is even worse for a prior use. Nevertheless, the problem mentioned in the background section of a prior art document from patent literature often is a good indicator whether the document is suitable as an appropriate starting point or not.

The most recent decision regarding the selection of the closest prior art, T 1841/11 of 3 December 2015, states that a document relating to a similar purpose as the claimed invention is not disqualified as closest prior document if there is another document which even relates to the same purpose. “The closest prior art should relate to the same or at least a similar purpose (or objective) as the claimed invention. Even if prior art relating to the same purpose is available, it is not excluded that a document relating to a similar purpose might be considered to represent a better - or at least an equally plausible - choice of closest prior art, provided that it would be immediately apparent to the skilled person that what is disclosed in the document could be adapted to the purpose of the claimed invention in a straightforward manner, using no more than common general knowledge. If, despite the availability of prior art relating to the same purpose as the claimed invention (here: manufacturing a semiconductor substrate comprising a silicon-germanium film), it is nevertheless considered appropriate to select as closest prior art a disclosure relating to a similar purpose (here: manufacturing a semiconductor substrate comprising a germanium film), at least one claimed feature corresponding to the purpose of the invention will generally appear as a difference over the closest prior art (here: silicon-germanium). However, this difference is not one which can legitimately be invoked in support of inventive step. The problem-solution approach presupposes that the skilled person has a purpose in mind from the very beginning of the inventive process, which in this case is the manufacture of a known type of semiconductor substrate comprising a silicon-germanium film. Within this conceptual framework, it cannot be logically argued that the skilled person would find no motivation to incorporate silicon-germanium. Moreover, an argument that it would not be straightforward to incorporate this difference into the teaching of the document considered to be closest prior art, or that this would require more than common general knowledge, would not, in such a case, constitute an argument in favour of inventive step, but rather an argument that this document is not in fact a promising starting point”.

It is often criticized that the selection of the appropriate starting point is based on hindsight. The author of this article cannot share this criticism. The selection of an appropriate starting point merely serves to make a reasonable pre-selection of documents departing from which there was a realistic chance of arriving at the invention in the sense that if one cannot arrive from these documents, then it is not possible to arrive from any other documents. (Otherwise one would have to test all documents.) As long as this pre-selection is not made to restrictive (e.g. by focusing on one closest prior art document), the hindsight in selecting an appropriate starting point does not appear to be problematic.

In T 1613/09 the appellant argued that D1 cannot be considered the closest prior art since starting from a "tower" computer is plainly contrary to the situation encountered by the inventor. This statement implies that, according to the appellant, the closest prior art should necessarily reflect the situation allegedly tackled by the person mentioned as inventor in the present application. It goes without saying that the actual situation in which the person mentioned as inventor was does not play any role in the assessment of inventive step.

The content of a prior art document has to be carefully assessed since it is read/interpreted in the knowledge of the subject-matter of the claims. It is important to note that according to the GL G-VII, 5.2, “the closest prior art must be assessed from the skilled person's point of view on the day before the filing or priority date valid for the claimed invention”. (By contrast, for the assessment of novelty, a prior document should be read as it would have been read by a person skilled in the art on the relevant date of the document. By "relevant" date is meant the publication date in the case of a previously published document and the date of filing (or priority date, where appropriate) in the case of a document according to Art. 54(3), see GL G-VI, 3). For example, when inventive step is assessed for a claim commencing with “A device for generating blue light…”, selecting an LED as closest prior art was not an appropriate starting point until the middle of the nineties of the last century since no technology was known until then how to produce blue light with LEDs[7]. Hence, LEDs were considered to be not “suitable for”[8] the generation of blue light. After the invention of blue LEDs, an LED could indeed be selected as a closest prior art. The situation is different for a claim starting with “A device for generating wind, comprising a, b, c…”. A grinding machine having features a, b and c may qualify as a closest prior art since it was known before the priority date that a grinding machine is (at least to a certain degree) suitable for generating wind.

To be continued

This article will be continued in the epi Information 4/2016

Any feedback is welcome and can be sent to or

  1. Visser, D., “The Annotated European Patent Convention”, 21st edition, 2013, p.115, section 6
  2. To be precise, it can also be a single embodiment (item) within a document. Art 56 EPC itself states that documents within the meaning of Art. 54(3) EPC must not be considered in deciding whether there has been an inventive step.
  3. This practice was, for example, criticized in the decision “Fisch-bissanzeiger” (BGH Xa ZR 138/05) by the Federal Court of Justice of Germany.
  4. section 3.5 of
  5. If this selection was not made, theoretically, one would have to test each available prior art document whether one could (and would) arrive at the subject-matter of the claim in an obvious manner from it until one finds such a document. In this case, the subject-matter of the claim is not inventive. If such a document is not found, one will have to go through all prior art documents available to show that the subject-matter of the claim is inventive.
  7. A comprehensive selection of decisions illustrating the selection of the closest prior art can also be found at “Case Law of the Boards of Appeal”, section I.D.3.4, 7th edition, 2013
  8. Hoekstra, J., “Methodology for Paper C – Training for the European Qualifying Examination”, Deltapatents, October 2009, p.151-152
  9. The Nobel Prize for physics in 2014 was awarded for "the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources". The “blue diode case” is also interesting for another reason. After one of the inventors sued his employer because the compensation he received for the invention was far too low, a court decided that his employer had to pay him 8.1 Mio US$.
  10. GL G-IV, 4.13 “An apparatus for carrying out the process of …etc.” is construed in the sense of merely meaning an apparatus that is suitable for carrying out the process.