18 August 2023

The impact of G2/21 on biotech patent drafting – extraordinary claims require extraordinary evidence

G2/21 is a recent Decision issued by the European Patent Office’s highest law-making court, the Enlarged Board of Appeal (EBoA). The details of the specific case are reported elsewhere and will not be discussed in depth in this article. The Decision of the EBoA, however, has important implications for patent Applicants, in the biotech field in particular, in relation to the amount of data that should be included in a patent application in support of the technical effect of a patent claim. In summary, while patent Applicants should always seek to include as much supporting data as possible in a patent application, for sufficiency of disclosure the amount of data required is related to the credibility of the claimed invention, whereas in relation to inventive step, post-filed evidence of a technical effect may be admissible under the circumstances outlined in G2/21.

Background and the concept of plausibility

In G2/21, the EBoA considered the issue of “plausibility”. The concept of plausibility of a technical effect is relevant to the requirements of both inventive step and sufficiency of disclosure. Both of these aspects are discussed in the G2/21 Decision, and must be considered by Applicants when deciding how much supporting data should be included in a biotech patent application.

It is important to note that the concept of “plausibility” per se is not a requirement for patentability in Europe, but rather it is linked to the question of whether an Applicant was actually in possession of the claimed invention at the time of filing the patent application. Prior to G2/21 at least, the relevant test for whether a patent application supported the technical effect of a patent claim was whether the effect was plausibility disclosed in the application as filed.

Where the technical effect is a feature of the claim, the “plausibility” of the technical effect is assessed under sufficiency of disclosure. An example of this is a claim in the European second medical use format, i.e., “Substance X for use in treating disease Y”. In this type of claim, the technical effect that must be disclosed in a patent application is a therapeutic property of substance X on disease Y.

Where the technical effect is not recited in the claim, however, plausibility of the technical effect is a requirement for inventive step rather than sufficiency.This situation arises frequently in inventions in the biotech field. For example, a claim to an antibody may have the format of “An antibody comprising the CDRs of SEQ ID NOs: 1-6”, and the technical effect in this case is a property of the antibody such as an improved specificity or binding affinity for an antigen in comparison to that of prior art antibodies.

As will be discussed below, it is this concept of the plausibility of a technical effect that the EBoA considered in detail in G2/21. The Decision provides guidance to Applicants in the biotech field on the amount of evidence required in relation to a technical effect in terms of both inventive step and sufficiency of disclosure.

Inventive step

The European Patent Office (EPO) assesses inventive step using a formula referred to as the “Problem and Solution” approach. The first step in this approach is to identify the closest prior art document, which is the document, selected from those identified in a prior art search by the Examiner (or by an Opponent in post-grant proceedings), that represents the most promising starting point for a development leading to the claimed invention. Typically, this is the document that is most closely concerned with the same problem as the claimed invention and/or has the most features in common.

Having identified the closest prior art document, a feature that distinguishes the claimed invention from the disclosure of the closest prior art is identified, and the technical effect provided by this distinguishing feature is then determined.

The purpose of the invention is defined as the achievement of this technical effect, and this is referred to as the so-called “objective technical problem”. Whether the claimed invention involves an inventive step is a question of whether it would have been obvious to a skilled person starting from the closest prior art document to solve the objective technical problem (i.e., provide the technical effect) by using the distinguishing feature.If using the distinguishing feature would have been an obvious approach based on the state of the art at the filing date, then the claimed invention cannot be considered to involve an inventive step. Conversely, an inventive step is acknowledged if the use of the distinguishing feature would not have been an obvious solution.

Significantly, when using the “Problem and Solution” approach, the technical effect is derived from the disclosure of the closest prior art document. However, the closest prior art document is not necessarily known to the Applicant at the filing date and is frequently only identified during the prosecution of the patent application or during opposition proceedings after the patent has been granted.Indeed, this is a frequent scenario in chemical and life sciences patent prosecution. In such cases, the Applicant cannot, however, be expected to include comparative data in the specification as filed in relation to prior art that they were not aware of when drafting the application. In order that patent Applicants are not unfairly penalised in this way, the EPO has, in principle, allowed Applicants to submit post-filed evidence to support the technical effect derived in light of the closest prior art document. However, different EPO Boards of Appeal (BoAs) have applied different criteria for the admissibility of such post-filed evidence, and it is for this reason that the issue of the criteria for the admission of post-filed evidence was considered by the EBoA in G2/21.

Briefly, the case at issue claimed a composition comprising two chemical compounds that were both known at the filing date to function as insecticides. The patent was granted by the EPO and subsequently opposed. The alleged technical effect was that the combination of the compounds provided an unexpected synergistic effect against certain species of moth. The Board of Appeal hearing the case took the view that inventive step was the only ground that was potentially relevant to the validity of the patent, and during the appeal proceedings, the Patentee submitted new post-filed data as evidence supporting the alleged technical effect. The Board’s view was that if the post-filed data was found to be admissible, then it provided evidence for the technical effect, and an inventive step could be acknowledged, whereas if the post-filed data were inadmissible, the patent would be found to be invalid for lacking an inventive step. The outcome of the case, therefore, was entirely dependent on the admissibility (or not!) of the post-filed evidence.

Both the Patentee and Opponent provided arguments based on previous EPO BoA Decisions in relation to the admissibility of the post-filed evidence. Based on these arguments, it appeared that, under similar circumstances, previous BoAs had applied different criteria when considering the admissibility of post-filed evidence for inventive step, such that in some cases it had been admitted into the proceedings, and in other cases, it had not been admitted. In view of this perceived conflict in the EPO BoA case law, the Board of Appeal hearing the case was unable to determine whether the post-filed data was admissible. Thus, the question of what are the requirements for admissibility of post-filed data to support a technical effect for inventive step, was referred to the EBoA for clarification.

In making the referral, the Board of Appeal reviewed the criteria for admissibility that had been applied by previous BoAs and identified three diverging approaches, each of which imposes a different burden on the Patentee in terms of the level of support required for the technical effect in the specification as filed:

  • The first approach identified by the Board, which imposes the most significant burden on the Patentee, was referred to as the “Ab initio plausibility” requirement. In this approach, in order for post-filed evidence in support of an inventive step to be considered admissible, the evidenced technical effect must have been at least plausible at the filing date. For example, the application as filed must have included a degree of data or a scientific explanation to justify the technical effect. In that sense, the post-filed evidence can be seen as reinforcing or elaborating on a concept that is at least alluded to in the specification as filed.
  • The second approach imposes a lesser burden on the Patentee, and was referred to as the “[Lack of] ab initio implausibility” requirement. In this line of case law, BoAs had taken the view that in order for the post-filed evidence to be admissible, the technical effect must not have been implausible at the filing date. For example, the technical effect does not necessarily need to have been discussed in the application as filed, but there must not have been a prejudice in the technical field or a prior publication indicating that the technical effect cannot be achieved.
  • Finally, the third approach identified by the Board was the “No plausibility requirement”. In this approach, BoAs have applied the principle of the free evaluation of evidence.

Each of these approaches imposes different requirements on the Applicant in terms of the level of supporting data that must be included when drafting a patent application. For example, the ab initio plausibility approach requires the Applicant to ensure that there is enough evidence in the application as filed to support an argument that any technical effect that may be derived in light of any possible closest prior art document is plausible in order for post-filed evidence to be admissible. This approach imposes a much higher bar for the level of supporting data required than the other approaches, such as the lack of ab initio implausibility approach.

In essence, the referring Board asked the EBoA firstly, whether post-published evidence should be excluded if the proof of the technical effect is based entirely on that evidence, and secondly, if that is correct, what are the requirements for admissibility; are they ab initio plausibility, or lack of ab initio implausibility?

In its Decision, the EBoA found that post-filed evidence supporting a technical effect may not be disregarded solely on the ground that it is post-filed. In relation to the requirements for admissibility, the EBoA found that a patent Applicant 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.

Although the EBoA avoided any reference to the term “plausibility”, this Decision appears to be good news for patent Applicants because it arguably equates to the lower bar requirement for the inclusion of data of the “[lack of] ab initio implausibility” approach. In view of the EBoA Decision, in order for post-filed data to be used in support of the inventiveness of a claimed invention, the technical effect must be derivable from the patent application, encompassed by the technical teaching, and embodied by the same originally disclosed invention. Future BoA Decisions will refine precisely what is meant by these terms, and one interpretation suggested by the referring Board is that the technical effect must not change the nature of the invention.

Despite this apparently relatively low threshold for the admissibility of post-filed evidence of a technical effect in inventive step, Applicants are advised to work on the basis that the higher ab initio plausibility standard still applies. Thus, best patent drafting practice should involve anticipating which features of the claimed invention could become distinguishing features in an inventive step analysis, and discussing the technical effect that they may provide, in order to provide robust basis for filing post-filed evidence of the effect, if necessary.

Sufficiency Of Disclosure

The EBoA in G2/21 also considered the case law on plausibility in relation to sufficiency of disclosure.

It is a legal requirement that at the filing date, a patent application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Article 83 EPC). In view of this requirement, the scope for using post-filed evidence is much narrower for demonstrating a sufficiency of disclosure than for inventive step.

This was confirmed by the EBoA in G2/21 in which it was found that proof of a claimed technical effect has to be provided in the application as filed, “in particular if, in the absence of experimental data in the application as filed, it would not be credible to the skilled person”. Again, the EBoA avoided reference to the term plausibility, and instead introduced the concept of credibility.

What this means is that, for a sufficient disclosure, the amount of data required in a patent application is inversely proportional to the level of credibility that the skilled person would give to the claimed technical effect. Thus, if, in the absence of experimental data, the skilled person would have found the claimed technical effect to be credible at the filing date, then little or no supporting data is required in the patent application. On the other hand, if the technical effect is a radical departure from the common general knowledge, or simply unknowable, for example, such that without experimental evidence it would not have been credible to the skilled person, then the patent application must include enough supporting data to evidence the technical effect.

As a consequence, in the absence of robust supporting data in the application as filed, in order to demonstrate sufficiency of disclosure the Applicant may need to rely, to some extent, on the state of the art and the skilled person’s common general knowledge. This reliance, however, may result in a tension (or a “squeeze”) between the need to demonstrate sufficiency of disclosure and also an inventive step.

The introduction of the concept of credibility by the EBoA should not alter current practice. The test for [lack of] sufficiency of disclosure, which is well-established by EPO BoAs, is whether there are “serious doubts substantiated by verifiable facts”. The severity of doubt in relation to a technical effect is dependent on the evidence provided in the patent specification, and, therefore, appears to be aligned with the concept of credibility.

In light of G2/21, the amount of supporting data that an Applicant must include in a patent application is based on how the invention would be understood by the skilled person. The significance of the contribution made by the invention to the relevant field should, therefore, be carefully considered when drafting a patent application. The more significant the contribution to the art, the greater the requirement for evidence supporting the technical effect.

To put it another way, to quote Carl Sagan, extraordinary claims require extraordinary evidence.