2.2. Departing from the problem-solution approach

Very early in its case law, the boards emphasised the obligation of objectivity when assessing inventive step; it is the objective rather than subjective achievement of the inventor which has to be assessed (see T 1/80, OJ 1981, 206; T 20/81, OJ 1982, 217; T 24/81, OJ 1983, 133; T 248/85, OJ 1986, 261). Starting out from the objectively prevailing state of the art, the technical problem is to be determined on the basis of objective criteria and consideration given to whether or not the disclosed solution is obvious to the skilled person. Although the problem-solution approach is not mandatory (see e.g. R 8/19), its correct application facilitates the objective assessment of inventive step. The correct use of the problem-solution approach rules out an ex post facto analysis which inadmissibly makes use of knowledge of the invention (T 564/89, T 645/92, T 795/93, T 730/96, T 631/00). In principle, therefore, the problem-solution approach is to be used; however, if exceptionally some other method is adopted, the reasons for departing from this generally approved approach should be stated.

In T 465/92 (OJ 1996, 32) the board did not take the problem-solution approach when assessing inventive step, and said this was merely one of several possible approaches, each with its advantages and drawbacks. There was no legal basis for prescribing a particular method for the assessment of inventive step under Art. 56 EPC. It took the view that all of the seven relevant citations came equally close to the invention. See also T 967/97 in the chapter I.D.3.1. "Determination of closest prior art in general".

In T 188/09 the board noted first that whatever approach was applied as an auxiliary means for the evaluation of inventive step of claimed subject-matter, in a given evidential situation it had to provide the same result, be it either in favour of or against inventive step. Therefore, even if the problem-solution approach was applied, the decision on inventiveness should be the same as if it had not been used. Citing T 465/92 (OJ 1996, 32), the board observed: "if an invention breaks new ground it may suffice to say that there is no close prior art rather than constructing a problem based on what is tenuously regarded as the closest prior art."

In case R 5/13 (as well as R 9/13, R 10/13, R 11/13, R 12/13 and R 13/13 which were all directed against T 1760/11 of 16 November 2012 date: 2012-11-16), the petitioners argued that they should have been allowed to discuss all the issues of inventive step of any stage of the problem-solution approach in respect of all possible starting points that they wished to rely on, despite the fact that the board had structured the discussion by first establishing which document or documents constituted the most promising starting point. The Enlarged Board in R 5/13 held that the board had not only followed the sequence for the debate announced in its communication annexed to the summons to oral proceedings, but by doing so it had also systematically applied the standard method of the problem-solution approach. The examination whether or not the subject-matter of a patent claim involved an inventive step according to the well-established problem-solution approach was a matter of substantive law. That was equally true for the determination of the closest prior art as the first step of the problem-solution approach, whether one document alone or a plurality of documents was taken as the starting point or most promising springboard aiming at the invention.

In T 68/16 the board stated that, as a rule, a division that does not use the problem-solution approach should indicate its reasons for doing so, if only to dispel the impression that it was acting arbitrarily. Although an opposition division should indeed keep in line with the established jurisprudence (i.e. by following the problem-solution approach), it was not formally binding on the departments of first instance. Only the department whose decision was appealed is bound by the ratio decidendi of the board (Art. 111(2) EPC). The board noted that the Guidelines in the version then applicable, stated at point G‑VII, 5, that any "deviation from this approach should be exceptional". Consequently, it held that a division that, in an exceptional situation, chooses not to use the problem-solution approach and does not explain its choice, did not commit a substantial procedural violation. The board noted however that in the case in hand using the problem-solution approach might have prevented the opposition division from presenting a defective reasoning. The Guidelines have since been amended and as of the 2018 version, the cited wording has been removed. The corresponding passage in EPC Guidelines G‑VII, 5 (April 2025 version) reads: “In order to assess inventive step in an objective and predictable manner, the problem-solution approach is applied.”

In T 2679/19 the opponent argued that the problem-solution approach was not the exclusive method for dealing with the consideration of inventive step and that, regardless of the differing features and of the objective problem, the skilled person was always looking for improvements. The board saw no reason to depart from the problem-solution approach in the case in hand, and found if it were assumed that the skilled person was always simply looking for "improvements" and recognised that an easy assembly was desirable (in fact also a problem to be solved), the skilled person would anyway not arrive at the subject-matter of claim 1. The further adaptations which would be required to arrive at the structure in claim 1 were based on purely subjective or hindsight considerations.