Reliance on a purported technical effect for inventive step (interpreting G 2/21)

September 25, 2023

The Enlarged Board of Appeal’s decision G 2/21 was noted for the abstract criteria it set for relying on post-published evidence to support an inventive step. We take a look at these criteria and the case from which the questions on this point of law were referred to interpret the decision.

The European Patent Office (EPO) considers an invention to involve an inventive step if it involves a non-obvious technical solution to a technical problem.

A patent application will usually provide evidence that the offered solution solves the problem it is suggested to solve in cases where this would not be immediately apparent or where there could be doubt as to this fact.

However, for one reason or another, a patent proprietor/applicant may find themselves having to rely on features of their invention which provide effects underpinning a solution to a problem for which no evidence was supplied when the application was made.

In the decision G 2/21, published earlier this year, the Enlarged Board of Appeal (EBA) of the EPO answered questions on a referred point of law relating to when post-published evidence may be relied upon in support of a purported technical effect for inventive step.

The board which referred those questions has recently had the task of interpreting the EBA’s answers and applying them to decide the case in which those questions arose. That case concerns a patent which claims mixtures of thiamethoxam with compounds according to formula Ia.

Both thiamethoxam and the compounds with which it is combined were known for their insecticidal activity before the patent application was made.

A synergistic effect, rather than a mere aggregation of effects, is required to avoid an invention being considered as a combination of features arrived at by solving several problems independently of one another (under the EPO’s “partial problem” approach), which can prove fatal in the assessment of an invention’s inventive step.

The patent includes a disclosure which alleges that mixtures of thiamethoxam and compounds according to formula Ia can produce an insecticidal activity which is greater than that which would have been expected based on their respective individual activities. In other words, that an insecticide composition according to claim 1 exhibits a synergistic effect.

For an inventive step to be acknowledged, the technical effect relied upon must be achieved over whole breadth of claim (see e.g., T 939/92).

Therefore, if the synergistic effect is only achieved with some of the claimed mixtures, then for some others of the claimed mixtures there is only an aggregation of known effects.

This is how the opponent (appellant) attacked the patent. The opponent submitted evidence which the EPO considered sufficient to prove that the synergistic effect is not achieved by all of the claimed mixtures.

So how should the proprietor (respondent) proceed?

One option is to concede that the claim is too broad and that it needs to be limited to mixtures for which the synergistic effect is achieved. In other words, a subset of the disclosed mixtures should be claimed. Unfortunately, in many cases this may be difficult to do without extending the content of the application as filed. In particular, a teaching in the application as filed of this specific subset would probably be required in order to avoid the EPO considering the application’s content as being extended by such a claim.

An alternative is to consider that the synergistic effect has been stated too broadly. For example, rather than all of the claimed mixtures having a synergistic effect on all insecticidal activity, perhaps all of the claimed mixtures have a synergistic effect on the insecticidal activity of a particular insect species. In this case, there would be no need to limit the claims.

Therefore, the alternative here seems quite appealing and it is the route taken by the proprietor.

However, the burden is now shifted to the proprietor to provide evidence that that this narrower synergistic effect is actually achieved (across the whole scope of the claim – although, note, the proprietor may well be given the benefit of the doubt on this point in the absence of any conflicting evidence).

In this case the proprietor attempted to provide this evidence in the form of additional test data which was not publicly available when the application was filed.

The questions that then arise are

1) can you rely on post-published evidence to support an asserted technical effect, and

2) what are the limits on this?

In G 2/21, the EBA answered these as

1) yes or, at least, it can’t be disregarded solely because it is post-published, and (more importantly)

2) “A patent applicant or proprietor may rely upon a technical effect for inventive step if the skilled person, having the common general knowledge in mind, and based on the application as originally filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.

The bolded wording is given some further context in the reasoning (r.93) where this is explained to be the relevant criteria “because such an effect does not change the nature of the claimed invention.”

How should we understand this?

One way that this could be understood is that if the alleged effect is a narrower version of what was set out to be achieved or reported to be achieved according to the application, the nature of the invention is unchanged. In such an event, the nature of the invention is not accidentally stumbled upon after filing. It is therefore hard to argue that “speculative patenting” is afoot, which according to at least one line of thought, ought to be discouraged as not properly fulfilling the “fundamental patent bargain”.

This could be distinguished from the situation where the as-filed patent application contains inadvertent disclosure of a combination of features which later turns out to have a benefit / purpose in a direction which is unrelated or substantially divergent from that in which the inventive activity (as judged from the testimony of the application as filed) was directed. This could be agreed to constitute an invention of a different nature.

Returning to the present case with this understanding would favour taking the post-published evidence into account because the claimed mixtures having a synergistic effect on the insecticidal activity of only a particular insect species, rather than all insect species, does not appear to change the nature of the claimed invention. This effect could therefore be considered as being “encompassed by the technical teaching and embodied by the same originally disclosed invention”.

The minutes from the oral proceedings held on 28 July 2023 reveal that the board did end up taking the post-published evidence into account, though the views of both parties on how G 2/21 should be interpreted and applied and the board’s final reasoning underlying the decision are not yet available. It will be interesting to read these once the written decision is published.