The EPO often considers data from after the filing date (“post-published data”) when assessing inventive step, but now it seems the Enlarged Board of Appeal may be asked to clarify when this practice should be allowed.

Under the EPO’s problem-solution approach for inventive step, the difference over the closest prior art is identified and linked with a technical effect. That effect can be crucial, as the objective technical problem considered by the EPO when assessing inventive step will involve attaining that effect. The effect usually needs to be supported by data, which may be in the application as filed or submitted during examination as post-published data.

In recent years there has been a line of case law which requires that a technical effect must be “plausible” at the filing date, i.e. based on the application as filed and the common general knowledge, in order to be included in the objective technical problem. Under this approach, post‑published data cannot be used to support a technical effect unless that effect is plausible at the filing date. Thus, when filing new patent applications, applicants have had to decide between filing early to avoid prior art, sometimes with little or no data and therefore at risk of not meeting the plausibility threshold, or later when more data become available, with the risk of facing additional prior art.

However, there is variation in how the plausibility standard is applied by the EPO, including different conclusions regarding the burden of proof and how the standard should be applied.  In addition, the general concept of plausibility has been questioned in other decisions, where applicants have been able to rely on post-published data without any need to show the effect was plausible at the filing date. Given the tensions in the case law, it is no surprise that the EPO’s Enlarged Board seems likely to be asked questions that may harmonise the approach in this area.

Broadly, the aim of the questions is to clarify whether a technical effect can be relied on when evidence for the effect rests solely in post-published data and what role, if any, plausibility should play in this assessment. The questions, which are yet to be finalised, are set out in the minutes of the oral proceedings involving Technical Board of Appeal 3.3.02 in case T0116/18, and concern an appeal filed by the opponent to the Opposition Division’s decision to maintain European patent EP2484209 as granted.

EP2484209 – Summary of facts

Granted claim 1 relates to an insecticide composition comprising a combination of two compounds, namely thiamethoxam and a compound represented by a genus.  For inventive step, the patentee argued that this combination of compounds provides a surprising synergistic effect.  The application as filed contains data showing that only two specific compounds from the genus, in combination with thiamethoxam, provide a synergistic effect.

The opponent argued that the data in the application as filed were not enough to make it plausible that a synergistic effect is achieved across the whole claim scope, for example because of the breadth of the genus.

The patentee filed its own post‑published data D21 and D22 showing that other combinations of compounds falling within the scope of claim 1 provide a synergistic effect.  However, the opponent argued that D21 and D22 cannot be relied on for inventive step because it was not plausible that the synergistic effect is achieved across the whole claim scope at the filing date.  In considering whether or not the patentee could rely on post-published data D21 and D22 the Board noted a divergence in the case law, which lead to the referred questions.

Diverging case law

According to the Board’s preliminary opinion prior to oral proceedings, the line of case law confirming that post‑published data supporting a technical effect can be taken into account only if the effect was already plausible at the filing date, e.g. T488/16, T1329/04 and T433/05, is not consistent with other case law such as T1422/12, T2371/13 and T31/18.

In T1422/12 a technical effect, which was not even mentioned in the application as filed, could be relied on for inventive step because it concerned “the same field of use” and did “not change the character of the invention”.  In T2371/13 the Board held that a lack of plausibility of a technical effect at the filing date was not a reason for disregarding post-published data. In T31/18 the Board held that the concept of plausibility of a technical effect at the filing date is incompatible with the EPO’s problem‑solution approach and that a technical effect can be relied on if it is “explicitly mentioned in the application as filed or at least derivable therefrom”. These all conflict with cases such as T488/16, T1329/04 and T433/05, which required an assessment of plausibility.

Further, in the Board’s preliminary opinion it is mentioned that even if one accepts that plausibility is required when relying on post-published data, then there is another divergence in the case law because it is not clear who must show plausibility (or indeed a lack of plausibility).  The Board contrasted T1329/04, where the burden rested with the patentee to show that it was plausible that a technical effect is achieved, with T184/16, where the burden rested with the opponent to show a lack of plausibility.

Provisional questions

In light of the above divergence in the case law, and based on the minutes of the oral proceedings, the Board is likely to refer questions to the Enlarged Board of Appeal along the following lines.  However, these questions are provisional, so they could change as the parties file further written comments.

If for acknowledgement of inventive step the patent proprietor relies on a technical effect and has submitted data or other evidence to prove such effect, such data or other evidence having been generated only after the priority or filing date of the patent (post-published data):

1. Should an exception to the principle of free evaluation of evidence (see e.g. G 1/12 reasons 31) be accepted in that the post-published data must be disregarded on the ground that the proof of the effect rests exclusively on such post-published data?
2. If the answer is yes (post published data must be disregarded if the proof of the effect rests exclusively on these data): can post-published data be taken into consideration if based on the information in the patent application the skilled person at the relevant date would have considered the effect plausible (ab initio plausibility)?
3. If the answer to the first question is yes (post published data must be disregarded if the proof of the effect rests exclusively on these data): can post-published data be taken into consideration if based on the information in the patent application the skilled person at the relevant date would have seen no reason to consider the effect implausible (ab initio implausibility)?

The final questions will become known once the written decision is issued. Once the questions are referred, there will be a chance for interested parties to file amicus briefs before a decision is handed down by the Enlarged Board. Given the complex questions at issue, it seems likely that we will have to wait until 2022, or even 2023, for an answer to these fundamental questions of European patent law. In the meantime, we will continue helping clients to find the best worldwide filing strategy given the shifting plausibility standard at the EPO.