T 1742/12 - What is the closest prior art

Key points

• The Board reviews the purpose and criteria for selecting the closest prior art under the problem-solution approach.
• As to closest prior art having a different purpose than the claim, the Board notes that there is no prohibition to consider "an inventive step assessment starting from a piece of prior art with a different purpose. To the extent that the difference in the intended purpose of the claimed invention imposes on it, the problem-solution approach requires it be determined whether it would be obvious to the skilled person to modify the prior art so as to provide these limitations. And it may be found that it would not."

T 1742/12 - link


Reasons for the Decision

The problem-solution approach and the closest prior art

5. Article 52(1) EPC provides that European patents shall be granted for any inventions that involve inter alia an inventive step, and Article 56 EPC (1973) stipulates 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.

6. The problem-solution approach is a well-established and successful tool for the assessment of the inventive step requirement as defined in Article 56 EPC (1973).

6.1 The problem-solution approach requires, in its first step, that prior art is identified and that then, in further steps, it is determined whether it would be obvious for the skilled person to modify or adapt the teaching of the selected prior art so as to arrive at the claimed invention. The selected piece of prior art is typically referred to as the "closest prior art".

6.2 The "closest prior art" is often characterised as being the "most promising springboard to the invention" (see in particular T 254/86, OJ EPO 1989, 115, Reasons 15; and T 656/90, Reasons 1.1).

6.3 If a piece of prior art can be identified as the "closest" prior art or the "most promising springboard" and it can be shown that, starting from this prior art, the claimed invention is non-obvious, then the claimed invention can only be even less obvious starting from any other piece of prior art, and therefore a detailed inventive step assessment starting from the other prior art can be dispensed with.

6.4 In the jurisprudence of the boards of appeal, criteria have been developed as to how, in the first step, the "closest prior art" can be selected from the available prior art. In particular, the "closest prior art" is normally that concerned with a similar use which requires the minimum of structural and functional modifications (see T 606/89, reasons 2).

6.5 It has, however, been acknowledged that the choice of the closest prior art may not always be unambiguous and that, in such a case, the problem-solution approach may have to be repeated starting from other pieces of prior art (see T 710/97, Reasons 3.2.1). It has also been observed that a piece of prior art on the basis of which the claimed invention is considered non-obvious cannot be "closer" than a document on the basis of which the claimed invention appears obvious, because it is evident in this situation that the former does not represent the most promising springboard from which to arrive at the invention (see T 824/05, Reasons 6.2).

6.6 In T 967/97 (Catchword I) and T 21/08 (Reasons 1.2.3) it was found that if the skilled person had a choice of several workable routes, i.e. routes starting from different documents, which might lead to the invention, the rationale of the problem-solution approach required that the invention be assessed relative to all these possible routes, before an inventive step could be acknowledged. Conversely, if the invention was obvious to the skilled person in respect of at least one of these routes, then an inventive step was lacking. In T 967/97 (catchword II) it was further stated that, if inventive step was to be denied, the choice of starting point needed no specific justification.

Choosing the starting point for the present invention

7. The appellant's position can be summarised as follows:

a) The correct application of the problem-solution approach obliges the board to choose the "closest prior art" as opposed to merely "a suitable starting point" (see letter of 18 May 2016, page 3, paragraph 4, and page 4, paragraph 1).

b) The closest prior art must be suitable for the intended purpose of the claimed invention, which D1 was not, because it did not relate to high performance computing HPC.

c) D6 did relate to HPC and was therefore closer than D1, so that "given the existence of D6, [...] D1 cannot be closest prior art" (page 5, paragraphs 1 and 2).

8. As regards point (a), the board disagrees with the appellant, and rather endorses the cited findings of T 967/97 and T 21/08. The board notes that these decisions are not isolated ones as the appellant seems to suggest but have been followed in several further board decisions (see e.g. the Case Law of the Boards of Appeal, I.D.2).

9. As regards point (b), the board agrees with the appellant that the intended purpose of the claimed invention is relevant in the inventive step assessment and that it may be simpler and more convincing to start this assessment from prior art sharing the intended purpose with the claimed invention. It may also happen that a piece of prior art is so "remote" from the claimed invention, in terms of intended purpose or otherwise, that it can be argued that the skilled person could not conceivably have modified it so as to arrive at the claimed invention. Such prior art might be referred to as "unsuitable". However, in the board's judgment, this does not prohibit the consideration of an inventive step assessment starting from a piece of prior art with a different purpose. To the extent that the difference in the intended purpose of the claimed invention imposes on it, the problem-solution approach requires it be determined whether it would be obvious to the skilled person to modify the prior art so as to provide these limitations. And it may be found that it would not.

10. As regards point (c), the board points out that the appellant's argument amounts to saying that knowing more can make an invention less obvious to the skilled person.

10.1 During oral proceedings, the appellant agreed to this counter-intuitive consequence of his position but argued that it had to be accepted if the problem-solution approach required it.

10.2 The board firstly disagrees that the problem-solution approach has this consequence and finds itself in agreement with the jurisprudence of the boards of appeal (see the above discussion).

10.3 Secondly, however, the board considers that this consequence is fundamentally unacceptable. If an argument showing that the claimed invention was obvious over some prior art, this argument cannot be refuted merely by the introduction of another piece of prior art. In the board's view, this would be an absurd situation in conflict with Article 56 EPC, and therefore be untenable.