Everything you always wanted to know about the Problem-Solution Approach but were afraid to ask

by M. M. Fischer (DE)

Even though European Patent Attorneys are expected to be well-versed in the correct application of the problem-solution approach, there are still questions which put even experienced practitioners on the spot, are not so easy to answer or have not yet been addressed by the Boards of Appeal. Following the maxim “If you do not ask you will never know”, this article presents a compilation of ten questions on the problem-solution approach and proposes answers mostly based on recently published articles, case law decisions and the author`s own experience in European patent law.

1. Who selects the closest prior art? And why?

One answer is given in the recent decision T 855/15: “It is irrelevant for the question of inventive step whether or not the "skilled person would [...] select" a piece of prior art "as a starting point to arrive at the invention". Article 56 EPC requires the assessment of whether an invention would be obvious to the skilled person "having regard to the state of the art". For this assessment, the deciding body will select one or more documents for consideration. However, no argument is required as to whether the skilled person would select a document. In fact, the board considers that a consideration of what the skilled person would do, in particular whether the skilled person "would select" a document, in order "to arrive at the invention as claimed" would amount to hindsight reasoning, because the skilled person would have to be assumed to know the invention before an argument could be made as to what he would do in order "to arrive at" it.”

Another answer is given by Dai Rees: “The skilled person picks a piece of prior art, recognizes a problem with it and, with the help of his common general knowledge (CGK) and/or a specific other piece of prior art but without any additional spark of invention, solves it, arriving at the claimed subject-matter. A major problem with this story is the question: why did the skilled person choose this piece of prior art to begin with? One thing we clearly cannot do is argue that he chose it because it was the closest prior art. If he knew it was the closest prior art he would also already know what the invention was, and that is one thing which is certainly not allowed. (Note that this is explicitly excluded in the English “Pozzoli” guidance.) It does not really help to say that he is given the piece of prior art to read; all that means is that someone else has to choose it, so then we have to specify both who and why! So all we can say is that he chooses this particular starting point because he can; it is simply one of the many prior art documents he might choose to start from. But this is not satisfactory; surely the skilled person, given a free choice, would choose as his starting point something which was most promising as a basis for development, any development. […] The problem and solution approach… does not actually introduce a skilled person until the last step. This introduces the possibility of a different interpretation of the approach which, I believe, fits the story-telling view better. It can be called the “multiverse” scenario. In this story instead of starting with the skilled person we start with a piece of prior art, any “feasible” piece of prior art. Which means there is not one possible story, but very many, in principle at least one for each piece of prior art. Of course, some stories will turn out to be plausible and some not. What about the skilled person? In this scenario the skilled person is determined not by the claimed invention but by the prior art. It can be posited that every piece of prior art has its own corresponding skilled person, a person who knows about that particular piece of prior art. ”[1]

2. Are all features of the claim equally important in the selection of the closest prior art?

No. It follows from the case law that the number of features in common may be a secondary criterion but is not the decisive criterion (see e.g. point 3.9 of the reasons of T 698/10). There are typically features in a claim which define the subject-matter globally and others which define the subject-matter locally. A global feature would e.g. relate to the type (in German also “Gattung”) of the claimed subject-matter. For example, the feature “wherein the screen is a flat screen” (in contrast to a cathode ray tube screen) could be considered as a global feature since it defines the screen as a whole (here in terms of the technology used), while a feature such as “wherein the screen has a main switch” could be considered as a local feature since it does not define the screen as a whole but only a (small, local) item of the screen which does not have influence on the screen as a whole. The global features should be anticipated by the closest prior art. The first words of an apparatus claim are often global features since they define the sort of subject-matter that is claimed. For example, a record cannot be used as the closest prior art for a claim starting with “A digital data carrier…”. Although the distinction between global and local features has no basis in the case law, it often correlates with the idea of “same purpose” or “same type” and is applicable and helpful in many cases.

In T 334/10 it was held that in medical use claims relating to a medical use of a compound the closest prior art can only be a document D38 which deals with the same or similar therapeutic use even if there is another prior art document D2 that shows a compound that is structurally closer to the claimed compound than the one of document D38 but does not show any therapeutic use of the compound in general or the claimed therapeutic use in particular.

T 1248/13 deals with “a casing for warhead components, characterized in that the casing is made up of a laser sintered material, wherein the laser sintered material comprises polymer particles and aluminium or magnesium powder”.

The Board argued that the fact that D4 does not disclose a casing for a warhead disqualifies said document as starting point for the problem-solution approach.[2]

By the way, the application of the problem-solution approach in stages with the first stage to be the selection of the closest prior art was confirmed by the Enlarged Board of Appeal in R 3/15 in which the Opponents argued that their right to be heard was violated because they were not allowed to present a complete line of argumentation against inventive step using the problem-solution approach starting from D1, while the Board of Appeal considered D1 to be an unrealistic starting point and considered D2 to be the closest prior art.

The Enlarged Board confirmed the appropriateness of the Board of Appeal`s conduct of the proceedings by stating: “In the present case, the Board considered that the case could be decided in respect of the issue of inventive step by systematically applying the problem-solution approach stage by stage. Thus, it systematically limited its decision-making and accordingly the discussion with the parties to determining the closest prior art first, before discussing the other aspects of the inventive step of the subject-matter claimed according to the patent proprietor's first auxiliary request.”

3. In which way is the purpose mentioned in the description of the application important for the selection of the closest prior art?

In T 2255/10 it was held that 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.

For this reason, statements of purpose must be read in conjunction with the claims. Merely inserting such a statement into the description does not entitle an applicant effectively to "veto" any inventive step objection based on a document which is unrelated to this purpose, if it is not plausible that the invention as claimed would actually achieve the stated purpose.

4. What is the common general knowledge (CGK), how does it differ from the rest of prior art and what else should I know about it?

The term “common general knowledge” is not used in the EPC. However it is inextricably linked to the notion of a skilled person that is used both in Art. 56 EPC and Art 83 EPC.[3] Common general knowledge is knowledge which the skilled person has at its immediate disposal (T 206/83), either because he knows it or is aware of the place where to find it. (One should not forget that, similar to CGK, the skilled person also has at his disposal the means and capacity for routine work and experimentation (Guidelines G-VII, 3).)

“According to T 1464/05 reason 5.2.2, the skilled person knows all the prior art (at least in the relevant field). I do not find this an appealing explanation for two reasons: (i) it again turns the skilled person into something which is clearly not a realistic person whose motivation one can reasonably judge; and (ii) it fails to distinguish between the CGK and all the rest of the prior art, although these are clearly treated differently when assessing how the skilled person would use them. While it seems reasonable to require that the skilled person has access to all the prior art, a fiction necessitated by the requirement of Art. 54 (2) EPC that all pieces of prior art have equal status, this does not mean that the skilled person must know the content of all the prior art.”[4]

That means the CGK is the mental furniture of the skilled person, the knowledge that the skilled person has at hand. The main difference between the CGK and the rest of the prior art is that it is normally obvious to combine a document with the CGK (see Guidelines G-VII, 6 (iii).). Hence, using common general knowledge as a secondary prior art in the problem-solution approach usually requires a bit less argumentation compared to using a normal publication, e.g. it needs hardly to be argued why such content would be consulted. As an analogy, if two prior art documents are considered to be two tiles, then the CGK may be considered to be the grout that sticks to them (=no incentive needed) and helps to fill the small gap that is needed to arrive at the claimed invention.

As another analogy from the world of computers, if the skilled person were a computer, then the CGK would be everything that is stored in his main memory (or that can be quickly load onto his main memory) that is quickly accessible, while all the rest of the prior art is stored on a harddisk that he carries with him but to which he has only slower access. He also needs an incentive to search for something on the harddisk and transfer it into the main memory.

Another difference between the CGK and the rest of the prior art is that if it is argued that prejudice exists that diverted the skilled man away from the alleged invention (which may be an indication for the presence of an inventive step in relation to an invention that rejects the prejudice), then this prejudice must be derivable from the CGK to reflect the common thinking in the relevant technical field. “A prior patent stating that a claimed invention is not realizable does not create a prejudice (T 206/83). Such a statement expressed in a patent is regarded as not being the expression of general opinion and is no proof of an existing prejudice because the specification of the prior art patent may be based on special premises or on the view of the drafter (T 19/81).”

Incidentally, technical standards may be treated in a similar manner as common general knowledge. In T 519/12 it was held that it is expected from the skilled person that he would exercise his skills in the framework of technical standards in force in his field of activity. No inventive activity can thus be derived from a feature that simply reflects the content of such a technical prescription (see point 3.5).

Finally, attention is drawn to decision T 1090/12 in which the Board of Appeal used the CGK to invalidate a claim but seems to abstain from providing proof of this CGK. This appears to be in contradiction with Case Law Book (8th edition, July 2016), section I.C.2.5 “Proof of common general knowledge: where an assertion that something is common general knowledge is challenged, the person making the assertion must provide proof that the subject-matter in question is in fact CGK (T 438/97, T 329/04, T 941/04, T 690/06).” In the current case, the board however seemed to be of the opinion that the situation is different if the board itself uses CGK to invalidate a claim.

5. Does CGK have a territorial dimension?

This question was answered in the negative in T 426/88. The appellant had argued that a book, written in German, was not a general reference book consulted by experts in that field in Great Britain. The board, however, adhered to the definition of the state of the art given in Art. 54 EPC 1973, according to which no account was taken of the location at which the skilled person exercised his profession. This is in contrast to jurisdiction from the UK: “The reason for this is that, whether one is concerned with the validity of a European Patent (UK), or a UK patent, one is concerned with a right in respect of the UK. It is true that the prior art may have been published anywhere in the world, but I do not think that alters the need for the skilled team to consider that art as if they were located in the UK. I do not think it matters that a fact was common general knowledge in (say) China, if it was not common general knowledge here. The position may be different if all the persons skilled in a particular art in the UK are acquainted with the position in China, but no point of that kind arises here.”[5] Australia removed the territorial limitation of CGK in 2013.[6]

6. Can a prior use be a secondary prior art disclosing the solution to the objective technical problem?

The author is not aware of any decision of the Boards of Appeal in which a prior use has been accepted as a secondary prior art containing the solution to the objective technical problem. A prior use can normally only be used as closest prior art (e.g. T 1464/05). The reason is that following the could-would approach there should be an incentive in the prior art as a whole that would have prompted the skilled person to apply the solution to the closest prior art. This incentive is typically found in a secondary prior art document that supplies the solution to the objective technical problem. However, a prior use is not a written teaching but only exists as such (e.g. as a publicly available apparatus) without any written incentive or hint that would for example show the skilled person that it solves the objective technical problem.[7]

(By contrast, common general knowledge is often used as a secondary prior art disclosing a solution to the objective technical problem. However, in T 1756/14 common general knowledge was taken as the closest prior art.)

7. When is the objective technical problem formulated as “providing an alternative solution”?

If the objective technical problem determined in the problem-solution approach is already solved in the closest prior art, then the problem itself does not have to be reformulated but can be considered to find an alternative solution to this problem (T 92/92, T 495/91). While it is often readily apparent in mechanical cases whether or not a technical effect is achieved (= objective technical problem is solved) by the claimed invention, this may not be the case in chemistry cases unless the patent application (or other evidence submitted by the applicant) makes it plausible that the technical effect is indeed achieved. In this case, the technical effect and hence the objective technical problem has to be reformulated, for example as a less ambitious problem (T 20/81). However, in many cases if no particular technical effect can be derived, one will end up again with having to reformulate the problem as to provide an alternative. However, experience shows that the problem “providing an alternative solution” often (not always) leads to the conclusion that the claimed invention is considered to be obvious. (If one solution is already known, then it may be obvious for the skilled person to substitute it with an (equivalent) alternative solution, for example based on his common general knowledge.) To mention a counterexample, a case in which an argumentation based on an “alternative solution” was successful is T 478/10.

8. Does the skilled person, in the assessment of obviousness, perform a search in order to find a secondary prior art or is he given the secondary prior art?

This question goes back to Derk Visser in the 24th edition of “The Annotated European Patent Convention”: “In the third stage of the problem and solution approach an assessment is made whether or not the solution of the problem is obvious for the skilled person. The assessment depends on the precise question that is being asked. There are two possible questions.

The first question that could be asked is: would a development by the skilled person starting from the closest prior art and guided by the problem to be solved result in the claimed invention? If yes, the invention is obvious. The skilled person must develop the closest prior art, which involves a prior art search for a solution of the problem. There are three issues with the first question. The first one is that there are usually many ways in which a problem can be solved. It is therefore a matter of chance that the search of the skilled person will result in the invention. The second issue is that the Guidelines and case law do not mention a search in the third stage. The third issue would give rise to arguments for and against finding the relevant prior art. However, such arguments are not addressed in the Guidelines. Rather, the Guidelines merely discuss whether or not a combination of certain prior art is obvious.

The second question is: is the solution, i.e. the combination of prior art that together disclose the features of the invention and found during the search under Art. 92, obvious for a skilled person in view of the problem of the closest prior art to be solved? The solution found during the search is presented to the skilled person and the question is whether the combination of prior art in the solution is obvious for him in view of the problem. If yes, the invention is obvious. An issue with this question is that it involves more hindsight than the first question. In the second question the complete solution is presented to the skilled person. In the first question only the closest prior art and the problem are given to the skilled person. Another important difference with the first question is that no search is carried out in the third stage of the problem and solution approach.

The Guidelines and case law do not explicitly state which question should be asked. However, section I.D.5 of the Case Law of the Boards of Appeal appears to imply that the second question is the correct one. The second question is also consistent with the procedure followed by EPO examiners during the assessment of inventive step.”[8]

The author of this article has to admit that he assumed the first question to be the correct one.[9] The author interprets the sentence: “Once the problem has been recognised, a search through the prior art for solutions seems fairly plausible;”[10] to be in line with the first question.

Moreover, it appears that each question defines “the solution” differently. With regard to the first question, the solution seems to be the teaching which solves that objective technical problem and is disclosed in a further prior art item. With regard to the second question, the solution seems to be the combination of the closest prior art with a further prior art item that together disclose the features of the invention. Neither the case law nor the Guidelines seem to give a clear definition of what is meant by “the solution”.

Regarding the third issue of the first question, it is methodologically not clear from the Guidelines whether the test for obviousness and the could-would approach is the same and which arguments can be put forward under the could-would approach? It appears that the could-would approach only addresses the question whether there is an incentive in the prior art as a whole that would prompt the skilled person to apply a further teaching to the closest prior art.[11] (A lack of “insurmountable difficulties” to apply a second teaching to the closest prior art is not enough to acknowledge an inventive step (T 142/84)). But is the fact that a secondary prior art is from a remote technical field that the skilled person would not find/read it also examined under the could-would approach? The Guidelines discuss the latter under the abilities of the skilled person at G-VII, 3, while the could-would approach is explained at G-VII, 5.3. However, contrary to the Pozzoli approach applied in the UK, the determination of the abilities of the skilled person is not an explicit extra stage of the problem-solution approach. It is also not clear whether technical incompatibilities or teaching-aways should also be examined under the could-would approach.

The question remains whether the two questions will effectively lead to a different outcome of the assessment of inventive step. Or is the difference merely a stylistic one which teaches us that arguments for or against obviousness should be presented in line with the second question (if it is indeed the correct one), i.e. try to avoid terms as “search” or “find” in the argumentation of the could-would approach?

9. Are problem inventions often acknowledged by the Boards of Appeal?

No. The discovery of an unrecognised problem may in certain circumstances give rise to patentable subject-matter in spite of the fact that the claimed solution is retrospectively trivial and in itself obvious. Problem inventions are rarely acknowledged by the Boards of Appeal (T 2/83, T 225/84, T 540/93, T 135/94,
T 1263/03). The latest decision in which a problem invention was acknowledged is
T 764/12 in which the technical contribution of the patent in suit resided in identifying a problem which was hitherto not recognised in the prior art, namely the need for protection during storage at ambient environmental conditions of a chewing gum base comprising environmentally degradable polymers. The arguments of the opponent that the claimed invention lacked inventive step because coating was well known to reduce degradation over time were not relevant.

10. Is it possible to change the closest prior art in an appeal?

Yes, but you have to provide arguments why you think that the closest prior art in the appealed decision is incorrect and why another document should be selected instead. Otherwise the appeal will be inadmissible. In T 1649/10, the Opposition Division denied patentability of the Main Request based on a document D10 as the closest prior art and then the teaching of D4 that suggested the use of the missing feature (a scatterer). The patent was maintained in amended form based on an auxiliary request. The opponent (appellant I) and the proprietor (appellant II) appealed. The Board of Appeal decided that the appeal of appellant II was inadmissible because in the statements of grounds it was argued that there was inventive step when taking D4 as the closest prior art in view of D10. The Board decided that such simple 'turning around' of the closest prior art is not allowed. Importantly, appellant II did not provide arguments why D4 should be considered as the closest prior art in the statements of grounds, which would have made the appeal admissible.

In T 55/11, appellant I swapped the closest prior art for the first time at the appeal oral proceedings (from D1 in combination with D13 to D13 in combination with D1). Appellant II requested that this new argument should not be admitted into the appeal proceedings. The board, in the exercise of its discretion, decided to admit the new arguments put forward by appellant I since D1 and D13 were both before the opposition division and had been extensively discussed throughout the proceedings. In addition, the combination of D13 with D1 compared to D1 with D13 does not change the inventive step argument in terms of technical features and problem to be solved. In addition this new argument is not incompatible with, or contradictory to, appellant I or II's previous case, nor does it raise any complex issues.

Any feedback is welcome. Please send it to: michaelfischer1978@web.de

  1. Rees, D. “Inventive Step: The Stories We Tell“, p.9-10, https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2952332
  2. In the assessment of novelty, the Board made the following noteworthy remark: “The question for assessing the criteria of novelty is not as much if the product achieved in D4 is "not unsuitable" [for a warhead component] but if the skilled person working in the field of casings for warheads would consider said sintered product to be obviously and directly suitable for such an application.”
  3. It should be noted that (the skilled person and his) CGK is also used in the assessment of novelty (Art. 54 EPC) for curing insufficiency of a prior art disclosure, in the assessment of added matter (Art. 123(2) EPC) and CGK also determines whether or not an error in an application can be corrected under R. 139 EPC, although neither Art. 123 (2) EPC, Art. 54 EPC nor R. 139 EPC explicitly mention the skilled person.
  4. Rees D., “Inventive Step: The Stories We Tell“, p. 10-11, weblink see above
  5. Arnold J in Generics (UK) Ltd (t/a Mylan) v Warner-Lambert Company LLC [2015] EWHC 2548.
  6. https://www.dennemeyer.com/insights/overview/news/164-update-on-the-ip-reform-in-australia-raising-the-bar/
  7. Chandler/Meinders, “C-Book”, 3rd edition, Carl Heymanns Verlag, 2010, p.77
  8. Visser, D., “The Annotated European Patent Convention”, 24th edition, H. Tel Publisher B.V., 2016, p.118
  9. “Problem and solution approach: Basic case law and recent development (Part II)” – EPI Information 4/2016
  10. Rees, D. ”Inventive Step: The Stories We Tell“, p.11, weblink see above
  11. On the other hand, the could-would approach explicitly mentions the skilled person so that it should be the right place to discuss the skilled person`s abilities.