3. Closest prior art
3.5. Similarity of the technical problem
A document serving as the starting point for evaluating the inventive merits of an invention should relate to the same or a similar technical problem or, at least, to the same or a closely related technical field as the patent in suit (T 495/91, T 570/91, T 989/93, T 1203/97, T 263/99, T 1634/06).
In T 439/92 the board pointed out that one of the criteria for determining the closest prior art was the problem already stated in the patent. In many cases it was reasonable for there to be a link between this problem and the prior art chosen as being closest. See also in this chapter I.D.4.2.2 "Problem formulated in the patent application as starting point".
In T 698/10 the board held that the closest prior art did not have to disclose all the problems solved by the claimed invention. In particular it did not have to disclose the objective technical problem, which was only determined in the second step of the problem-solution approach based on the technical effect(s) provided by those features distinguishing the invention as claimed from the closest prior art. See also T 638/16, T 1148/15, T 1112/19.
In T 325/93 the board stated that the problem addressed by the application was neither derivable nor indeed recognisable from the disclosure of D2 which, according to the department of first instance and the appellant, represented the closest prior art. As early as T 686/91, another board had observed that a document not mentioning a technical problem which was at least related to that derivable from the patent specification did not normally qualify as the closest prior art for inventive step purposes, however many technical features it may have in common with the subject-matter of the patent concerned (see also T 410/93, T 708/96, T 59/96, T 827/00, T 979/00, T 496/02, T 1666/16).
In T 644/97 the board concluded that a technical problem arising from a "closest prior art" disclosure which was irrelevant to the claimed subject-matter (in the sense that it did not mention a problem that was at least related to that derivable from the patent specification) had a form such that its solution could practically never be obvious, because any attempt by the skilled person to establish a chain of considerations leading in an obvious way to the claimed subject-matter was bound to fail (see also T 792/97 and T 599/03). However, according to the board in T 1408/09, it is not a requirement for obviousness that the starting point in the prior art addresses the same technical problem as the claimed invention.
In T 835/00 D1 did not mention any of the problem aspects addressed by the claimed invention. As a consequence, a technical problem was created which was unrelated to the actual disclosure of D1 but whose solution was then found to be obvious in the light of the disclosure of D2. The board referred to T 686/91 and stated that it was a fatal defect that a prior art disclosure from which no relevant technical problem could be formulated without inappropriate hindsight had been chosen as a starting point for the application of the problem-solution approach, because without such hindsight any attempt to establish a logical chain of considerations which might lead to the claimed invention inevitably ran into difficulties at the start, for want of a relevant identifiable goal or object. If the relevant problem was not derivable from the alleged closest prior art, the measures for its solution were a fortiori not derivable. In other words, the invention was not obvious in the light of such art. See also T 548/03, T 1898/07, T 638/16.
In T 25/13 D4 related to tumble dryers and so came under domestic appliances, a field neither the same nor even closely related to that of the invention, namely automotive technology. For that simple reason, it could not be "the closest prior art". The board, however, held that opponents were essentially free to choose the starting point for assessment and that their choice then had implications for the technical knowledge of the relevant skilled person.
- T 2463/22
In T 2463/22 the opposition division had held that the prior uses had not been proven beyond reasonable doubt (up to the hilt), in particular with regard to whether the products of the prior uses had actually been delivered. The parties before the board focused on which standard of proof had to be applied in view of G 2/21 and T 1138/20 and whether the applicable standard had been met. In the respondent-proprietor’s view, T 1138/20 was an isolated decision, not compatible with G 2/21.
On the required standard of proof, the present board observed that G 2/21 recognised that different concepts as to the standard of proof had been developed in the case law. According to T 1138/20 only one standard should be applied, namely "the deciding body must be convinced, taking into account the circumstances of the case and the relevant evidence before it, that the alleged fact occurred".
In the present board's view, under the principle of free evaluation of evidence, it was always decisive in the evaluation of evidence that the members of the deciding body were personally "convinced". Moreover, they had to always be convinced of whether, as stated in T 1138/20, "the alleged fact has occurred". The board stated this was true regardless of which standard of proof was applied. The standard of proof refers to the nature or degree of conviction that the members of the deciding body must have to be satisfied that an alleged fact occurred (see T 832/22).
According to the board, and with reference to a UK House of Lords decision, two important aspects had to be stressed. Firstly, that the standard of proof is related to the required degree of conviction of the members of the deciding body. Secondly, that it is not related to what is evaluated by the deciding body. Hence, also when a lower standard of proof such as the balance of probabilities is applied, the deciding body must assess whether or not the alleged fact indeed occurred. In other words, also when such a standard of proof is applied, the question is not whether the alleged fact might have occurred with some probability. The board considered G 2/21 (points 31 and 45 of the Reasons) consistent with this understanding.
The more specific question as to whether there was only a single standard of proof or more than one could be left unanswered according to the board. The board held that if the deciding body was convinced beyond reasonable doubt that an alleged fact had occurred, there was no need to decide how many standards of proof there were and which one was applicable (see T 832/22).
The board then gave some consideration to the assessment of factual allegations using the beyond reasonable doubt standard of proof. The European Patent Organisation being an independent international organisation, the board stated the standard had an autonomous meaning within this autonomous legal order. Secondly the board agreed with T 832/22 that it seemed expedient to focus on the term "reasonable".
The board then considered the prior uses, focusing especially on prior use relating to the sale of product 5 (sample of a powder mix from a specific lot number), the content of the sample and whether it was available to the public. In view of all the information (including invoices, affidavit, emails, test report, excerpt from database), which also involved evidence provided by a third party (the buyer), the board was convinced beyond reasonable doubt that product 5, with a specific lot number, was sold prior to the effective date of the patent. Since it had also been shown that product 5 disclosed all features of claim 1, lack of novelty prejudiced the maintenance of the patent as granted. Concerning the third auxiliary request, product 5 was suitable for use as closest prior art. The board referred to the reluctance sometimes in the case law to treat an object of a prior use as the closest prior art. Often, there was neither information on what the object did and what properties it had in the technical environment in which it was applied nor on how the process for its manufacture could be modified. These considerations indeed spoke against regarding a prior use as a suitable starting point for assessing inventive step. In the case in hand however, the skilled person was faced with a different situation. The board concluded that the third auxiliary request did not involve an inventive step. The decision of the opposition division was set aside and the patent revoked.