In the second stage, one establishes in an objective way the technical problem to be solved. To do this one studies the application (or the patent), the closest prior art and the difference (also called "the distinguishing feature(s)" of the claimed invention) in terms of features (either structural or functional) between the claimed invention and the closest prior art, identifies the technical effect resulting from the distinguishing features, and then formulates the technical problem.

Features which cannot be seen to make any contribution, either independently or in combination with other features, to the technical character of an invention cannot support the presence of an inventive step (see T 641/00). Such a situation can occur for instance if a feature only contributes to the solution of a non-technical problem, for instance a problem in a field excluded from patentability. For the treatment of claims comprising technical and non-technical features, see G‑VII, 5.4. The criteria for determining whether a feature, even if non-technical in isolation, contributes to producing a technical effect in the context of the invention are explained in G‑II, 3 and sub-sections, for different types of subject-matter listed under Art. 52(2).

In the context of the problem-solution approach, the technical problem means the aim and task of modifying or adapting the closest prior art to provide the technical effects that the invention provides over the closest prior art. The technical problem thus defined is often referred to as the "objective technical problem".

The objective technical problem derived in this way may not be what the applicant presented as "the problem" in the application. The latter may require reformulation, since the objective technical problem is based on objectively established facts, in particular appearing in the prior art revealed in the course of the proceedings, which may be different from the prior art of which the applicant was actually aware at the time the application was filed. In particular, the prior art cited in the search report may put the invention in an entirely different perspective from that apparent from reading the application only. Reformulation might lead to the objective technical problem being less ambitious than originally envisaged by the application. An example of such a case would be where the originally stated problem is the provision of a product, process or method demonstrating some improvement, but where there is no evidence that the claimed subject-matter is thereby improved over the closest prior art uncovered in the search; rather, there is only evidence with respect to more distantly related prior art (or possibly none at all). In this case, the problem has to be reformulated as the provision of an alternative product, process or method. The obviousness of the claimed solution to that reformulated problem must then be assessed in the light of the cited prior art (see T 87/08).

The extent to which such reformulation of the technical problem is possible has to be assessed on the merits of each particular case. As a matter of principle any effect provided by the invention may be used as a basis for the reformulation of the technical problem, as long as said effect is derivable from the application as filed (see T 386/89). It is also possible to rely on new effects submitted subsequently during the proceedings by the applicant, provided that the skilled person would recognise these effects as implied by or related to the technical problem initially suggested (see G‑VII, 11 and T 184/82).

It is noted that the objective technical problem must be so formulated as not to contain pointers to the technical solution, since including part of a technical solution offered by an invention in the statement of the problem must, when the state of the art is assessed in terms of that problem, necessarily result in an ex post facto view being taken of inventive activity (see T 229/85). Where the claim refers to an aim to be achieved in a non-technical field, however, this aim may legitimately appear in the formulation of the problem as part of the framework of the technical problem to be solved, in particular as a constraint that has to be met (see G‑VII, 5.4, and G‑VII, 5.4.1).

The expression "technical problem" is interpreted broadly; it does not necessarily imply that the technical solution is an improvement to the prior art. Thus the problem could be simply to seek an alternative to a known device or process which provides the same or similar effects or is more cost-effective. A technical problem may be regarded as being solved only if it is credible that substantially all claimed embodiments exhibit the technical effects upon which the invention is based. Criteria for deciding whether lack of reproducibility of the claimed invention is to be treated under Art. 56 or Art. 83 are explained in F‑III, 12.

Sometimes, the objective technical problem must be regarded as an aggregation of a plurality of "partial problems". This is the case where there is no technical effect achieved by all the distinguishing features taken in combination, but rather a plurality of partial problems is independently solved by different sets of distinguishing features (see G‑VII, 6, and T 389/86).