T2759/17 – Closest prior art for assessing the inventive step of chemical inventions
In decision T 2759/17 dated 7 October 2021, the Board of Appeal decided that, particularly in the field of Chemistry, a disclosure within a prior art document can only be considered to represent a suitable starting point for assessing inventive step, if the skilled person would have realistically started from said disclosure.
The EPO applies the “problem-solution approach” for assessing whether a claim possesses inventive step. In the problem-solution approach, there are three main stages:
- determining the “closest prior art”;
- establishing the “objective technical problem” to be solved; and
- considering whether or not the claimed invention, starting from the closest prior art and the objective technical problem, would have been obvious to the skilled person.
There is divergent EPO case law on the correct approach to take when determining the closest prior art to a claim.
Following decisions T 1241/18, T1450/16 and T855/15, the deciding body (e.g., examining division or opposition division) is responsible for selecting the closest prior art. In this approach, the skilled person and their expectations, prejudices, knowledge and abilities do not play any role in the selection of the closest prior art. Consequently, following this approach, it is not possible to disregard a technical teaching on the ground that the skilled person would not have considered it to be the most promising: each and every disclosure within a document can be selected as a suitable starting point for assessing inventive step.
However, following decisions T254/86 and T2148/14, the technical teaching from which the skilled person would have realistically started as the more promising springboard towards the invention needs to be determined. In this approach, the skilled person is considered to generally look for a disclosure that aims at a purpose or effect that is the same as or at least similar to the one underlying the patent in question. Thus, it is possible to reject an inventive step attack on the ground that the skilled person would not have realistically selected the specific disclosure, on which the attack relies, as a starting point.
Recent decision T2759/17 considered which of the two approaches set out in the case law is the correct approach for determining the closest prior art to a claim, particularly in the field of Chemistry.
Decision T2759/17 dealt with an appeal, by the opponent, against the decision of the opposition division to maintain European patent number EP 2009993 in amended form. The opposition division had found the claims of auxiliary request 1, filed during the opposition proceedings, to be allowable.
Claim 1 of auxiliary request 1 was directed to the use of a composition, comprising components A and B, for suppressing biofilm formation and removing an already-formed biofilm. The appellant (opponent) argued that claim 1 of auxiliary request 1 lacked inventive step over cited document E1.
E1 disclosed a number of different detergent compositions. The appellant argued that any of the detergent compositions disclosed in E1 could be considered a suitable starting point for assessing the inventive step of claim 1 of auxiliary request 1. The respondent (patent proprietor) argued that selecting certain compositions disclosed within E1 to constitute the closest prior art involved the impermissible use of hindsight: the skilled person would not realistically have started from those compositions. In other words, the appellant and the respondent disagreed over what was the closest prior art to claim 1 of auxiliary request 1.
The Board of Appeal (herein “the Board”) considered which of the two approaches to determining the closest prior art, found in the EPO case law, should be applied. The Board stated that “it is the Board’s firm conviction that the skilled person is the relevant point of reference right from the start of any inventive step assessment. Determining whether an invention is inventive involves technical considerations, and those have to be made through the eyes of the skilled person. Excluding the skilled person for part of the inventive step assessment would lead to artificial and thus technically meaningless results”. Accordingly, the Board held it to be correct to apply the approach set out in decisions T254/86 and T2148/149.
In reaching the decision to apply the approach set out in decisions T254/86 and T2148/14, the Board made specific reference to patents and applications within the field of Chemistry. Specifically, the Board stated that: “at least in the field of Chemistry…the skilled person normally does not arbitrarily pick any existing prior art disclosure and only then starts to think about the technical field in which it might be applied and what effect it could possibly achieve”9; and if the skilled person is not taken into account when determining the closest prior art, “the disclosure coming structurally closest to the claimed subject matter might always be chosen…this…would imply the use of hindsight”9. From this, it appears that the Board is of the opinion that the approach to determining the closest prior art set out in decisions T254/86 and T2148/14, involving considering what the skilled person would have considered the most promising springboard toward the invention, should always be applied when assessing the inventive step of inventions within the field of Chemistry.
As a consequence of applying the approach set out in decisions T254/86 and T2148/14, the Board disagreed with the appellant on which composition in E1 constituted the closest prior art to claim 1 of auxiliary request 1. The Board argued that the appellant’s inventive step arguments were based on an ex post facto approach, i.e., hindsight. The Board concurred with the respondent regarding which disclosure in E1 constituted the most promising springboard to the invention and found claim 1 of auxiliary request 1 to not be obvious to the skilled person starting from this disclosure.
Often an examining division or an opponent will select a particular embodiment disclosed in a prior art document as the closest prior art to the subject matter of a chemical claim based purely on structural similarities or number of features in common. Decision T2579/17 provides applicants and patent proprietors with additional basis to argue that an inventive step attack, starting from a specific embodiment disclosed in a prior art document, should be rejected, where the skilled person would not have realistically started from said embodiment.
- T2759/17 – Closest prior art for assessing the inventive step of chemical inventions - September 14, 2022
- T1791/16 – Clarity in opposition proceedings - December 1, 2021
- Novelty based on the purity of a chemical compound in Europe - June 1, 2021