2.1. Objective assessment of inventive step

Article 56 EPC gives a negative definition of the "inventive step" required under Art. 52(1) EPC, by setting out that 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". In order to assess inventive step in an objective and predictable manner, the so-called "problem-solution approach" was developed, consisting of the following stages:

(a) determining the "closest prior art",

(b) assessing the technical results (or effects) achieved by the claimed invention when compared with the "closest state of the art" determined,

(c) defining the technical problem to be solved, the object of the invention being to achieve said results; and

(d) considering whether or not the claimed solution, starting from the closest prior art and the objective technical problem, would have been obvious to the skilled person (G 1/19, OJ 2021, A77, point 26 of the Reasons; see also G 2/21, OJ 2023, A85; T 939/92, OJ 1996, 309; T 15/93; T 433/95; T 917/96; T 631/00; T 423/01; T 215/04; T 1621/06; T 1183/06; T 824/07; see also EPC Guidelines G‑VII, 5 – April 2025 version).

On application of the problem-solution approach to claims comprising technical and non-technical aspects (especially in the case of computer-implemented inventions), see in this chapter I.D.9.2., and for its application to claims directed to chemical inventions, see in this chapter I.D.9.9.1.

The boards frequently cite R. 42(1)(c) EPC as the basis for the problem-solution approach. R. 42(1)(c) EPC requires that the invention be disclosed in such terms that the technical problem (even if not expressly stated as such) and its solution can be understood. Problem and solution are thus component parts of any technical invention. The problem-solution approach was primarily developed to ensure objective assessment of inventive step and avoid ex post facto analysis of the prior art (see for example T 2679/19). As long ago as T 26/81 (OJ 1982, 211), R. 27(1)(d) EPC 1973 (in the version in force until 31 May 1991; the predecessor of current R. 42(1)(c) EPC) was recognised as clearly binding.

A solution claimed as non-obvious is patentable only if it actually has the alleged effect. According to T 2001/12, a doubt that the invention as claimed is capable of solving the problem defined in the application may have the following consequences: a) If the claim fails to specify those features which are disclosed in the application as providing the solution to the problem, then an objection under Art. 84 EPC 1973 may properly arise that the claims do not contain all the essential features necessary to specify the invention; b) if this is not the case, but, having regard to the prior art, and irrespective of what may be asserted in the description, it does not appear credible that the invention as claimed would actually be capable of solving the problem, then an objection under Art. 56 EPC 1973 may be raised, possibly requiring a reformulation of the problem. See also T 862/11 which also dealt with the distinction between the requirements of sufficiency of disclosure (Art. 83 EPC), clarity of the claims (Art. 84 EPC), and inventive step (Art. 56 EPC).

In T 967/97 the board stated that the problem-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 (see also T 970/00, T 172/03).

According to the board in T 270/11, the problem-solution approach does not require that the application specify what feature is responsible for producing precisely what advantage or technical effect. All that is required for inventive step is that the claimed subject-matter is not obvious to the skilled person in the light of the prior art (Art. 56 EPC). It is common practice to take features from dependent claims or the description and insert them into an independent claim with a view to rendering the subject-matter patentable and to cite the effects and advantages associated with those features as a basis for (re-)formulating the technical problem. To determine the objective technical problem, the technical results and effects achieved by the claimed invention as compared with the closest prior art must be assessed.

In T 2517/11 the board held – with regard to “hidden” features – that the problem-solution approach developed in the boards' case law entailed consideration of all technical features comprised in the closest prior art, regardless of whether they were directly identifiable or hidden, since even hidden features were publicly available. For more on this topic see chapter I.D.3.6 "Implicit features".

The board in T 1761/12 held that the problem-solution approach involved analysing the steps the skilled person would have taken to solve the predefined objective technical problem, and nothing else. Any further reflection on whether the associated changes to the closest prior art identified in this analysis made sense had the effect, in practice, of adding the related aspects of other problems to the objective technical problem initially defined.

In T 320/15 the board held that the problem-solution approach did not consist of a forum in which the appellant (opponent) could freely develop various attacks based on diverse prior art documents in the hope that one of them would succeed.

Instructive summaries of the case law on the problem-solution approach can be found in a number of decisions; see e.g. R 9/14, T 519/07, T 698/10.