Is it Plausible? EPO proceedings stayed after referral to Enlarged Board of Appeal

Author: Deborah Hart
IP News

The EPO has paused all proceedings where the determination of whether an invention contains an inventive step is solely reliant on data that was not publicly available at the filing date until the Enlarged Board has published a decision in case G2/21.

The issue of plausibility relates to whether it is plausible that the invention concerned works as asserted. This arises at the EPO in relation to both sufficiency and inventive step, depending on whether the technical feature forms part of the claims, or is relied upon as an advantage for inventive step arguments. In life sciences and chemical cases, additional data is often provided post-filing to show that the claimed invention has a technical effect or advantage other those in the prior art. As the applicant is not always aware of the relevant prior art prior to filing, the ability to rely on post-filed data can be crucial in establishing that a claimed invention has a technical effect, and so is inventive.


The referral arises from appeal T116/18 in the opposition to EP2484209, which relates to an insecticide. The patent as filed provided data to show that some example compounds had a synergistic effect against two species of moth. During the opposition proceedings the Opponent provided data to show that some other compounds which fell within the scope of the claims did not have a synergistic effect against one of the moth species.  In response the Patentee submitted further data to show a synergistic effect of the example compounds against a third moth species. The Opponent argued that the effect of the compounds against the third moth species was not made plausible from the application as filed, and so the additional data should not be taken into consideration.

The Board of Appeal considered that there are three diverging lines of case law on whether post-filed data is admissible when assessing inventive step:

1. Ab initio plausibility – where plausibility of the technical effect must be established by the application as filed for post-filed evidence to be taken into account.

2. Ab initio implausibility – where post-filed evidence may be disregarded only if there are reasons for the skilled person to doubt that the technical effect had been achieved at the filing date.

3. No plausibility – where there is no requirement for plausibility at the filing date, as this is incompatible with the EPO’s problem solution approach to assessing inventive step.

In light of this divergence, three questions were referred to the Enlarged Board of Appeal, which are summarized below:

If inventive step relies on post-published evidence,

1) should post-published evidence be disregarded if proof of the technical effect is solely provided by the post-published evidence?

If the answer to (1) is yes, is the standard for post-published evidence being taken into account that

2) the technical effect was plausible at the filing date (ab initio plausibility)?; or

3) the technical effect was not implausible at the filing date (ab initio implausibility)?

The Enlarged Board is expected to issue a decision within the next 18 months, and it could have a major impact on applications in the life science and chemical areas, where additional post-filed data is frequently used to provide a direct comparison with the closest prior art, or to demonstrate a technical effect. If the bar for plausibility is raised, or the effect needs to be plausible from the application as filed, then applicants may need to postpone filing until evidence is available to fully support a technical effect. In addition, more pre-filing searches may be required to make sure that the closest prior art is identified, and some comparative data is included in the application, to ensure strong patents.

close popup

IP updates signup

Subscribe to our IP news updates mailing list

If you would like to receive our IP updates, please complete the form below. By signing up, you are agreeing to receive IP updates from us, but you can unsubscribe at any time.

* indicates required
Select your IP interests

Please select all the ways you would like to hear from Beck Greener:

We take your privacy seriously and you can manage your preferences or unsubscribe at any time by clicking the link in the footer of our emails. For information about our privacy practices, please visit our website at

We use Mailchimp as our marketing platform. By clicking below to subscribe, you acknowledge that your information will be transferred to Mailchimp for processing. Learn more about Mailchimp's privacy practices here.