The Board of Appeal (EPO) decision T 1087/15 solidifies recent liberal Case Law regarding the selection of the closest prior art as starting point for inventive step attacks in EP opposition proceedings:

(https://www.epo.org/law-practice/case-law-appeals/recent/t151087eu1.html).

The decision finds 'closest' being merely a label, and follows other Board of Appeal decisions of late, e.g., T 0855/15 or T 2057/12, which reasoned that for the selection of the closest prior art – the first step of the problem solution approach – no argument is required as to why the skilled person would select that prior art, as long as it belongs to the same or a neighboring technical field of the person skilled in the art or to its common general knowledge.

In the case at hand, the patent proprietor argued that a document selected as starting point by the opponent was inappropriate, since it was remote from the invention, and thus the formulation of the objective technical problem – another step of the problem solution approach – would inevitably have to involve hindsight. Moreover, the document was allegedly inappropriate, because another document would have been a much better starting point since disclosing more features of the attacked claim.

However, the Board first reasoned generally that (emphasis added):

…an 'appropriate' starting point for an inventive step objection can be any piece of prior art in the same field as, or a closely neighbouring field of, the claimed invention, …”.

Then the Board reasoned more specifically – and this in rather unambiguous words – that (emphasis added):

To be overly restrictive as regards possible starting documents for an inventive step attack is unnecessary since less promising starting points would anyway make an obvious modification thereof (in order to reach the claimed subject-matter) more difficult than when starting from a more promising document. Therefore, rather than the 'appropriateness' of a document being analysed in too great detail in advance of the formulation of an inventive step attack, less promising starting documents will ultimately be exposed by resulting in unsuccessful inventive step attacks. In this regard it should be remembered that 'closest' prior art is merely a label given to the piece of prior art from which an inventive step attack starts and which is considered to be the most promising. In many cases it may indeed not be possible to identify whether one piece of prior art is necessarily 'closer' than another piece of prior art, and doing so may well artificially restrict inventive step considerations using the problem/solution approach”.

Regarding the argument of the proprietor that the selection of an inappropriate document as a starting point would involve hindsight when formulating the objective technical problem, the Board responded that (emphasis added):

In as far as hindsight is concerned, knowledge of the claimed invention is however absolutely necessary in order to formulate the objective technical problem, irrespective of how 'close' the prior art document is to the claimed invention; the features differentiating the claimed subject-matter from the starting document must be identified, their technical effect determined and thus the problem to be solved formulated. In as far as such knowledge of the claimed invention is labelled as 'hindsight', then indeed this particular type of hindsight is a necessity in order for the technical problem to be formulated on an objective basis. As long as there is no reason (primarily a technical reason) why the content of the document selected as the closest prior art would itself not be suitable or compatible for use with respect to the subject-matter claimed, any analysis of 'how close' the prior art starting document is judged to be to the claimed invention is not something which should exclude it from being the closest prior art.”.

According to this decision of the Board, the opponent should be free in selecting a starting point for an inventive step attack in EP opposition proceedings, seemingly without having to provide any argument, as to why the selected document is appropriate as starting point.

It is noteworthy that this approach of the Board is quite similar to the approach taken by the German Federal Court of Justice (BGH). According to the BGH, whether the skilled person would start from a certain piece of prior art, does not depend on this piece of prior art being the closest prior art to the claimed invention. In fact, classifying a piece of prior art as the closest prior art is neither sufficient (“Olanzapin”) nor necessary (“Fischbissanzeiger” and “Gestricktes Schuhoberteil”).

It is also noteworthy that this approach of the Boards seems, at first glance, to contradict the (recently amended) guidelines of examination of the EPO, as the guidelines state that (emphasis added):

“..applying the problem-solution approach from different starting points, e.g. from different prior-art documents, is only required if it has been convincingly shown that these documents are equally valid springboards. In particular in opposition proceedings the structure of the problem-solution approach is not that of a forum where the opponent can freely develop as many inventive step attacks as he wishes in the hope that one of said attacks has the chance of succeeding (T 320/15, Reasons 1.1.2)

This statement could be misunderstood in the sense that it is necessary to show, with respect to each document selected as starting point, why the document is appropriate, i.e., why it is closest prior art, or at least closer prior art than other prior art, with respect to the claimed invention. This would obviously contradict the latest decisions, particularly the conclusion that no argument is required why the skilled person would select a certain document, and that less promising starting documents will ultimately be exposed by resulting in unsuccessful inventive step attacks.

Consequently, the statement in the guidelines can only be meant to limit the total number of inventive step attacks, but not to rule out certain inventive step attacks because of inappropriateness of the selected document.

Practical impact:

Providing arguments why a certain document is selected as starting point for an inventive step attack seems to become less and less critical for the opponent. The opponent seems to be free in selecting any document, and providing arguments why the skilled person would have obviously reached the claimed invention from that document. However, the opponent may not be allowed to select an unduly large number of documents as different starting points, without providing arguments in this case, why each starting point is equally promising and therefore needs to be considered for assessing inventive step.