The technical problem arising may have to be reformulated, in particular in less ambitious terms, if it appears in view of experimental evidence that the combination of features in the claim does not solve this problem over the whole area defined in the claim (T 20/81, OJ 1982, 217; T 39/93, OJ 1997, 134). See also T 2001/12.

It belongs to the well-established jurisprudence of the boards of appeal that where a specific problem is identified in the description, the applicant or patentee may be allowed to put forward a modified version of the problem particularly if the issue of inventiveness has to be considered on an objective basis against a new prior art which comes closer to the invention than that considered in the original patent application or granted patent specification (T 184/82, OJ 1984, 261; T 386/89). Applying the problem and solution approach, when the original technical problem defined in the application as filed has to be modified to take account of the closest prior art, the objective, more restrictive, problem is determined by the underlying remaining features of the claim (T 39/93, OJ 1997, 134). However, reformulation of the problem is only allowable, if the new problem can be deduced from the application as filed (T 13/84, OJ 1986, 253), i.e. within the limit of the original description (T 162/86, OJ 1988, 452). As a matter of principle, any effect provided by the invention may be used as a basis for reformulating the technical problem, as long as that effect is derivable from the application as filed (T 386/89, see Guidelines G‑VII, 5.2 – November 2018 version). A reformulation of the problem also may be appropriate if an alleged effect of a described feature could be deduced by the skilled person from the application in the light of the prior art or if new effects submitted subsequently during the proceedings were implied by or related to the technical problem initially suggested. In relation to new effects it was not permissible to change the nature of the invention (T 344/89, T 2233/08).

In T 184/82 (OJ 1984, 261) the board said that "regarding the effect of the invention" reformulation of the problem could be allowed "provided the skilled man could recognise the same as implied or related to the problem initially suggested". The problem may thus be restated to meet a less ambitious objective (see also T 106/91, T 339/96, T 767/02). It was also ruled in T 13/84 (OJ 1986, 253) that a reformulation of the problem was not precluded by Art. 123(2) EPC 1973 if the problem could be deduced by the skilled person from the application as filed when considered in the light of the closest prior art (T 469/90, T 530/90, T 547/90, T 375/93, T 687/94, T 845/02). In T 818/93 the board added that it sufficed if the reformulated problem could be deduced later by comparing the application with the closest art. Since features from the drawings might be incorporated into the claims, and also into the description in support of the claims (T 169/83, OJ 1985, 193), those features' effects and advantages might also be used as a basis for reformulating the problem, provided this problem could clearly be deduced from the above comparison. T 162/86 (OJ 1988, 452) added that it should still be possible in appeal proceedings to define the original problem more precisely, within the limits of the original description.

According to T 39/93 (OJ 1997, 134), the technical problem as originally presented in the application or patent in suit, which was to be regarded as the "subjective" technical problem, might require reformulation on the basis of objectively more relevant elements originally not taken into account by the applicant or patentee. This reformulation defined the "objective" technical problem. The latter represented the problem ultimately remaining, i.e. the technical effect achieved by the subject-matter (features) as defined in the claim.

Following on from this case law, the board in T 1397/08 confirmed that, in accordance with the problem and solution approach for assessing inventive step in chemistry, the technical problem could be reformulated, and in certain circumstances actually had to be, since the only factor of importance in determining the problem objectively was the result actually achieved in relation to the closest state of the art. There was nothing to prevent the problem as first formulated from being modified, even at the appeal stage, as long as the spirit of the original disclosure of the invention was respected. See also T 2371/13, T 659/15.

In T 716/07 with regard to the reformulation of the problem the board considered whether the examples in the closest prior art document and the patent in suit were comparable to the extent that the alleged effect was convincingly shown to have its origin in the distinguishing feature of the invention (T 197/86, OJ 1989, 371; T 1835/07). Then the board determined whether it was probable that this effect had been achieved over the whole range of the claims of the patent in suit (see T 1188/00), and finally whether the effect was related to the problem to be solved as disclosed in the application as filed. In this case the comparison between the examples in the prior art and those in the patent showed an unexpected effect.

In T 143/13 the board observed that, according to the problem and solution approach, it is the problem described in the patent application that is normally used as the starting point for assessing inventive step. In the decision under appeal, the step of assessing whether the problem defined in the application had been solved had been omitted. Nevertheless, the problem had been reformulated in terms that had not been invoked by the appellant (applicant). The justification provided for the reformulation of the problem was that the originally defined problem was artificial. However, the board could not see why. The reformulation of the problem in the decision under appeal was not considered to be appropriate.

In T 564/89 the appellant submitted that any amendment of the technical problem had to be in line with Art. 123(2) EPC 1973. The board stated that this article was not concerned with the issue of whether or not an objectively reformulated technical problem could be used in the course of the so-called problem and solution approach. Art. 123(2) EPC 1973 would only come into play if an amended technical problem were incorporated into the description itself (T 276/06).

In T 732/89 the respondent submitted that the "hot/wet" performance of the claimed composites, although admittedly better than that of the control composition, corresponded to a completely new effect which could not be incorporated into the technical problem without contravening Art. 123(2) EPC 1973. The board did not agree with this line of argumentation and referred to T 184/82 (OJ 1984, 261) where a redefinition of the problem regarding the effect of an invention was allowed provided that the skilled person could recognise the same as implied or related to the problem initially suggested. In the case in point the board took the demonstrated effect into account in the formulation of the technical problem and stated that in determining which effect was crucial and which was merely accidental (the so-called "bonus effect"), a realistic approach had to be taken, considering the relative technical and practical importance of those effects in the circumstances of a given case (see also T 227/89).