In W 12/89 date: 1989-06-29 (OJ 1990, 152) the board referred, inter alia, the following questions to the Enlarged Board of Appeal:

"Does an International Searching Authority have the power to carry out a substantive examination of an international application in respect of novelty and inventive step when considering under Art. 17(3)(a) PCT whether the application complies with the requirement of unity of invention set forth in R. 13.1 PCT?

If an International Searching Authority does have such power, in what circumstance does it have an obligation to carry out such a substantive examination?"

The Enlarged Board of Appeal delivered its decision in G 1/89 (OJ 1991, 155; see also the opinion given by the Enlarged Board in G 2/89, OJ 1991, 166, in response to a related referral by the President of the EPO). It found that in accordance with normal terminology, the term "examination" or "substantive examination" referred to the activities of the authorities responsible for deciding on patentability, such as the examining division of the EPO, or, in the case of the PCT, to the activities of the IPEA and/or the designated Office. Obviously, an ISA did not have any power to carry out such activities. The Enlarged Board held that an ISA might only form a provisional opinion on novelty and inventive step for the purpose of carrying out an effective search. This opinion was in no way binding on the authorities referred to above. The same principle applied also when an ISA considered that an international application did not comply with the requirement of unity of invention set forth in R. 13.1 PCT on an "a posteriori" basis. Such consideration had only the procedural effect of initiating the special procedure laid down in Art. 17 PCT and R. 40 PCT and was, therefore, not a "substantive examination" in the normal sense of that term. According to the decision an assessment of whether a single general inventive concept existed was to be undertaken only in so far as this was necessary to establish whether the invention complied with the requirement of unity when implementing the procedure laid down in Art. 17 PCT and R. 40 PCT. Such an assessment was provisional and did not constitute a substantive examination in the sense of an examination as to patentability (see W 6/90, OJ 1991, 438).

The Enlarged Board further noted that consideration by an ISA of the requirement of unity of invention should, of course, always be made with a view to giving the applicant fair treatment and that the charging of additional fees under Art. 17(3)(a) PCT should be made only in clear cases. In particular, in view of the fact that such consideration under the PCT was being made without the applicant having had an opportunity to comment, the ISA should exercise restraint in the assessment of novelty and inventive step and in borderline cases preferably refrain from considering an application as not complying with the requirement of unity of invention on the ground of lack of novelty or inventive step (see W 24/90, W 23/91, W 43/91). In W 1/97 the board held that there was no such clear case where the ISA, having already searched part of the subject-matter, was still not in a position to identify several separate inventions.

Following the Enlarged Board's conclusions in G 1/89 and G 2/89, the boards repeatedly used a lack of novelty or inventive step in the general inventive concept underlying the invention to justify a finding of lack of unity (see W 17/89, W 27/89, W 18/90 and W 19/90). In W 10/92 the board stressed that the problem-solution approach was to be applied to unity of invention (W 16/91, W 21/91).

In W 17/03 the ISA had considered that the absence of common technical features and an allegedly different problem solved would be sufficient to demonstrate lack of unity between groups of inventions. The board suggested that the ISA's approach to the determination of the problem appeared to stem from the belief that what was required was the same analysis as that used to determine the problem when using the problem and solution approach to evaluate inventive step, possibly because differences and problems are involved in both situations.

The board stated that it was not convinced that the investigation of technical relationships for unity with the aid of common problems underlying the inventions is necessarily the same as the analysis that is used to determine the problem when using the problem and solution approach to evaluate inventive step. The board gave the following reasons:

(1) The evaluation of unity involves comparing problems solved (or effects achieved) by different claims, whereas the evaluation of inventive step is carried out on a single claim. As a result, when examining unity, the problems solved by different claims must be considered in the light of each other and cannot be determined in isolation in an absolute sense.

(2) In the evaluation of inventive step, the idea is to define a problem based on the distinguishing features that is essentially as narrow as possible, but not involving elements of the solution. On the other hand, in the evaluation of unity, these restrictions do not apply, since the overall object is to find out what the claims involved have in common, i.e. if the respective inventions are so linked as to form a single general inventive concept.

Thus, the specific problems solved by the different inventions with respect to the closest prior art might need gradual refinement, in particular generalisation starting from the problem directly solved, to find out whether or not there was a common denominator that still distinguished the inventions from the said prior art.