EPO referral G2/21: Can post-filed evidence be used to demonstrate the existence of a technical effect for patentability?

In recent European Patent Office (EPO) Decision T 116/18, the Board of Appeal has referred important questions to the Enlarged Board of Appeal (EBA) regarding the issue of to what extent an invention must be plausible from the application as filed. A decision on this issue by the EBA would have important ramifications for how much experimental data is required to be included in a patent application, especially in the chemical and pharmaceutical sectors.

The issue of whether a technical effect is plausible from the original disclosure of a patent application is a controversial one in European patent law and is subject to much debate. There is no statutory requirement for plausibility in the European Patent Convention (EPC), but the criterion has been found necessary for patentability in many Board of Appeal decisions. According to established EPO case law, where a technical effect is recited in a claim (for example in medical use claims), its plausibility from the application as filed is a requirement for whether an invention is sufficiently disclosed (Article 83 EPC). On the other hand, where a claim does not recite a technical effect (such as a claim to a chemical composition per se), but the achievement of a technical effect is relied upon for inventive step, the plausibility of the technical effect from the application as filed has been found in certain decisions to be an important requirement for inventive step (Article 56 EPC). The case from which the present referral originates deals with the issue of plausibility under inventive step and the use of post-filed evidence to demonstrate the existence of a technical effect.

In many cases, a claimed invention (such as a pharmaceutical or chemical composition) is only inventive because it achieves some unexpected technical effect that it would not be obvious from the prior art would be associated with the claimed composition. In such cases, data to demonstrate the technical effect is often included in the application as filed. However, in others, data is not included in the application as filed, and the application merely contains an assertion that said technical effect is achievable. In other cases, the application as filed does not even contain a reference to the achievement of the effect. In the latter two scenarios, post-filed evidence is often filed during prosecution of a patent application or during opposition proceedings to demonstrate the existence of the technical effect. Post-filed evidence is very often filed where the problem underlying the invention must be reformulated in view of prior art that the patentee was not aware of when the application was filed. For example, data is often provided to demonstrate an unexpected improvement over said prior art.

The case from which the present referral originates concerned claims relating to an insecticide composition comprising a combination of known insecticidal compounds and an alleged synergistic effect associated therewith. The application as filed contained evidence of a synergistic effect against the insect pest species – S. litura and P. xylostella – at certain concentrations. During opposition proceedings, the opponent was able to demonstrate with data and argumentation that a synergistic effect against these above species was not credibly achieved across the scope of the claims for these species. However, using post-filed evidence, the patentee was able to demonstrate a synergistic effect against a different pest species, C. suppressalis. The problem underlying the invention could thus be reformulated as the provision of synergistic insecticidal activity against the species C. suppressalis. The opponent objected that whilst the post-filed data showed that this problem had been solved, it was not plausible from the application as filed that the claimed compositions solved such a problem due to the absence of data showing activity against C. suppressalis, and that as a result, the patentee’s post-filed data should not be taken into account when reformulating the problem underlying the invention. Without the patentee’s post-filed data, there was no evidence supporting a synergistic activity against C. suppressalis and the question of whether the patentee’s post-filed data could be taken into account would thus determine whether or not the claimed compositions were inventive. 

The Board of Appeal decided to refer questions on plausibility to the EBA, as, in their view, there were three diverging lines of case law regarding to what extent post-filed data can be relied upon by patentees to demonstrate the existence of a technical effect. The Board considered the three lines of case law to be:

1) Ab initio plausibility cases;

2) Ab initio implausibility cases; and

3) No plausibility cases.

The Board considered a referral necessary to ensure uniform application of the law and because points of law of fundamental importance had arisen.

In the ‘ab initio plausibility’ line of case law, the Board identified a principle that the plausibility of a technical effect must be established in the originally filed application by direct evidence of the technical effect such as experimental data or scientific reasoning; only then could post-filed data be considered. In the ‘ab initio implausibility’ line of case law, post-published evidence could only be disregarded if the skilled person would have legitimate reasons to doubt that the purported technical effect had been achieved at the filing date. For example, if common general knowledge at the filing date indicated to the skilled person that the technical effect was not achievable. In the ‘no plausibility’ line of case law, the concept of using plausibility as a way to determine the admissibility of post-filed data was rejected altogether and found incompatible with the EPO’s problem and solution approach for assessing inventive step.

The Board of Appeal thus referred the following three questions to the EBA.

  1. Should an exception to the principle of free evaluation of evidence (see e.g. G 3/97, Reasons 5, and G 1/12, Reasons 31) be accepted in that post-published evidence must be disregarded on the ground that the proof of the effect rests exclusively on the post-published evidence?
  2. If the answer is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have considered the effect plausible (ab initio plausibility)?
  3. If the answer to the first question is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have seen no reason to consider the effect implausible (ab initio implausibility)?

Answers to these questions from the EBA may have important ramifications for the validity of patents and affect best practice regarding drafting and prosecuting patent applications at the EPO. For example, if the EBA answers ‘Yes’ to questions 1 and 2 but ‘No’ to question 3 (approving an ‘ab initio plausibility’ standard), this would mean that applicants only receive patents for subject-matter for which data or other substantiation is contained in the application as filed that makes plausible the technical effect relied upon for inventive step. This might have the greatest impact on practice in fields such as pharmaceuticals where, quite often, patent applications directed to broad novel classes of compounds are filed with limited data demonstrating the effect of said compounds. On the other hand, if the EBA approves a ‘no plausibility’ requirement, this could open the door to considerably more ‘speculative patenting’ where applicants are granted patents for merely theorising that an invention is possible.

In the referral decision, the Board expressed concern that the ‘ab initio plausibility’ standard would place a very high burden on applicants where a reformulation of the problem underlying the invention was required in view of prior art unknown at the filing date, since post-filed data would not be able to be provided in support of any technical effect that was not plausible from the originally filed application. This risks undermining decades of case law allowing the reformulation of the technical problem and relying on post-published evidence to show that the newly formulated problem is solved.

Interestingly, the Board questioned whether the ab initio plausibility and implausibility standards were compatible with the principle of free evaluation of evidence, and what the legal basis was for preventing a patentee from relying on fact evidence relevant to inventive step, and from preventing a Board from taking into account evidence that it finds decisive. The Board also raised the issue of whether Article 56 EPC indeed provides legal basis for plausibility, commenting that Article 56 EPC simply states that an invention must be not obvious in view of the prior art, whereas the rationale for plausibility is whether or not the invention had indeed been made at the filing date (a separate criterion). The Board also made references to other commentators who had made similar observations.

There is some chance that this EBA referral will not be admitted on the basis that the points of law are not of fundamental importance and that the three lines of case law discussed above are not truly divergent. However, in the event that the referral questions are admitted, the EBA’s answers to these questions have the potential to significantly change practice at the EPO and best practice for drafting strong patent applications to be prosecuted in Europe.  

Key contacts

Charlie Dempster
Managing Associate