Thu 9th Feb 2023

Inventive Step at the European Patent Office: Post-Published Evidence and Plausibility

In an article for The Life Sciences Lawyer first published in January 2023, partner Roona Deb discusses the admissibility of post-published evidence for the assessment of an inventive step at the EPO.

The Enlarged Board of Appeal (EBA) of the European Patent Office has been presented with a new referral (G2/21) concerning the admissibility of post-published evidence for the assessment of inventive step in relation to European Patent No. 2 484 209. The outcome of this referral may have important ramifications for how much experimental data is required to be included in a patent application at the time of filing, particularly in the chemical, pharmaceutical and life sciences sectors.


Assessment of Inventive Step

The European Patent Office (EPO) assesses the presence of an inventive step in patent claims by applying the long-standing problem-solution approach. The problem-solution approach requires three main steps:

  1. determining the closest prior art;
  2. establishing the objective technical problem to be solved in view of the closest prior art; and
  3. considering whether or not the claimed invention, starting from the closest prior art and the objective technical problem, would have been obvious to the skilled person.


With regard to step (ii), the objective technical problem is formulated on the basis of a technical effect provided by one or more features which distinguish the invention as claimed over the closest prior art. An inventive step may be acknowledged if the claimed invention attains the technical effect and thus solves the objective technical problem across the entire scope of the claim in a non-obvious way. The technical effect typically needs to be supported by experimental data, particularly in the chemistry, pharmaceutical and life sciences sectors where results may be more unpredictable.


As experimental data may be limited at the early stages of invention development, Applicants in the chemistry, pharmaceutical and life sciences sectors may have to file patent applications with limited data. Under current practice, if adequate supporting data are not present in the application as filed, data submitted during examination (or opposition) as post-published evidence may be taken into consideration for the assessment of inventive step. However, the EBA’s decision may alter the circumstances under which this practice is allowed.


Background – European Patent No. 2 484 209

European patent No. 2 484 209 (“the patent”) owned by Sumitomo Chemical Company, Limited was opposed by Syngenta Limited on multiple grounds including lack of inventive step. The Opposition Division rejected the opposition and upheld the patent. The decision was appealed (T0116/18). The Board of Appeal decided that maintenance of the granted patent rests on the admissibility of post-published data relied upon by the proprietor to support a technical effect.


Claim 1 of the patent as granted is directed to an insecticide composition comprising a combination of two compounds, thiamethoxam and a second generic compound represented by a Markush formula Ia, both of which have known insecticidal activity.  The application as filed included data demonstrating a synergistic effect between thiamethoxam and two specific compounds within formula Ia, against two insect species S. litura and P. xylostella.


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 entire scope of the claims. However, in their defence, using post-filed evidence, the proprietor was able to demonstrate a synergistic effect against a different pest species, C. suppressalis.


The Board of Appeal decided that if the proprietor’s post-published data were admitted, then an inventive step could be acknowledged. (In this case, the objective technical problem could be reformulated as the provision of synergistic insecticidal activity against the species C. suppressalis, and the solution provided by the combination of compounds of granted claim 1 would be considered non-obvious.) However, if the post-published data were not admissible, then the claimed subject-matter would lack an inventive step on account of being merely an obvious alternative insecticide composition. The admissibility of the post-published evidence is thus pivotal to the outcome of the appeal.


Conflicts in existing case law

The Board of Appeal considered there to be three diverging lines of case law regarding the extent to which post-published evidence can be relied upon by patent proprietors to demonstrate the existence of a technical effect in support of inventive step.


Ab initio plausibility

According to this line of case law, an inventive step may only be acknowledged if the application makes it at least plausible that the claimed subject-matter provides the desired technical effect, and thus solves the objective technical problem. Supplementary post-published evidence typically may not serve as the sole basis to establish that the problem is solved. This standard follows Decision T1329/04 (Factor-9/John Hopkins), and is widely adopted at the European Patent Office (see for example, Decisions T488/16, T415/11, T1791/11 and T895/13.) Under this standard, applications based on speculative assertions that are not commensurate with the actual technical contribution to the art would not proceed to grant. In Decisions T1642/07 and T1599/06, the Board of Appeal stipulated that a technical effect could be made plausible by an appropriate theoretical explanation or information.


Ab initio implausibility

Another line of case law provides that post-published evidence may only be disregarded if the skilled person would have legitimate reasons to doubt that a purported technical effect would have been achieved on the filing date of the patent in suit. In other words, according to this line of case law, post-published evidence is taken into account as long as the purported technical effect is not implausible.


This standard of implausibility has been applied in Decision T578/06 (Pancreatic cells/IPSEN), where the Board of Appeal highlighted that the EPC does not require any experimental proof for patentability and considered that the disclosure of experimental data or results in the application as filed and/or post-published evidence is not always required to establish that the claimed subject-matter solves the objective technical problem. The Board further emphasized that the establishment of plausibility is only relevant when examining inventive step if doubts about the suitability of the claimed invention to solve the technical problem addressed were substantiated. Other Decisions applying this standard of implausibility include T536/07 and T1437/07.


No plausibility

There have also been instances where the Boards of Appeal have disregarded the concept of plausibility, and have taken into consideration post-published evidence demonstrating a technical effect of which there was no plausible demonstration in the original application (see T31/18 and T 2371/13). Here, the Boards took the view that the requirement for a plausible demonstration of a technical effect in the original application is incompatible with the problem-solution approach on the basis that the closest prior art in view of which the objective technical problem is formulated, may not be known to the Applicant at the filing date of the application.


Questions referred to the Enlarged Board of Appeal

In view of the divergent case law and the cruciality of the post-published evidence to the outcome of the appeal, the Board of Appeal referred the following questions to the EBA:

“If for acknowledgment of inventive step the patent proprietor relies on a technical effect and has submitted evidence, such as experimental data, to prove such an effect, this evidence not having been public before the filing date of the patent in suit and having been filed after that date (post-published evidence):

  1. Should an exception to the principle of free evaluation of evidence (see e.g. G3/97, Reasons 5 and G1/12, Reasons 31) be accepted in that the post-published evidence must be disregarded on the ground that the proof the effect rests exclusively on such post-published evidence?
  2. If the answer is yes (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 (post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can 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)?”

The answers to these questions will likely harmonise the approach taken by the European Patent Office in its assessment of inventive step, and provide more certainty for Applicants on the requirements for admitting post-published evidence. 


Brief Communication of the Enlarged Board of Appeal

On 13th October 2022, the EBA issued a brief communication in advance of the oral hearing that took place on 24 November 2022, highlighting issues of potential significance.


In the present referral, question 1 highlights that imposing rules on when post-published evidence can or cannot be considered would appear to go against the principal of free evaluation of evidence.


The EBA specifically noted: “…..the principle of free evaluation of evidence does not appear to allow disregarding evidence per se insofar as it is submitted and relied upon by a party […] and is decisive for the final decision. Disregarding such evidence as a matter of principle would deprive the party submitting and relying on such evidence of a basic legal procedural right generally recognised in the contracting states and enshrined in Articles 113(1) and 117(1) EPC.


From this statement, it appears that the EBA preliminarily considered answering “no” to the first question which may obviate the requirement for plausibility entirely, when relying on post-published data to support inventive step. However, the EBA did subsequently provide guidance on referred questions 2 (ab initio plausibility) and 3 (ab initio implausibility), and from the EBA’s comments, it seemed that it was leaning towards ab initio implausibility:


“It is then on the basis of the application documents and this technical teaching that a purported technical effect relied upon for inventive step is to be assessed as to whether the skilled person, having the common general knowledge in mind, would have had any significant reason to doubt it.


In the absence of any such doubts, the reliance on postpublished evidence, such as experimental data, for the purported technical effect would seem to serve as a potential source for a deciding body to conclude whether or not it is convinced of said technical effect when deciding on the inventiveness of the claimed subject-matter.”


The EBA also pointed out that the technical effect relied upon for inventive step arguments needs to be encompassed by the technical teaching of the claimed invention from the application as filed and "embody the same invention". This is in line with established case law relating to reformulation of the technical problem which stipulates that any effect provided by the invention may be used as a basis for the reformulation of the technical problem, as long as the effect is derivable from the application as filed, or the skilled person would recognise the effect as implied by or related to the technical problem initially suggested.


The final decision of the EBA is eagerly awaited and expected to be issued in Q2-Q3 2023. The EBA is not bound by any opinions expressed in its preliminary communication and its opinions may, of course, have changed following arguments presented by the parties at the hearing.


Concluding remarks

The EBA decision may alter current practice and filing strategies. In particular, in the life sciences and chemical sectors, there is often a need to strike a balance between filing early to secure the filing date and delaying filing in order to obtain (additional) experimental evidence to demonstrate the technical effect of the invention.


If the EBA’s decision restricts opportunities to rely upon post-published evidence to support inventive step, then Applicants may want to consider taking more time before filing to increase the amount of evidence/data included in new filings in order to better support the claimed invention.


Conversely, if the EBA’s decision lowers the threshold for admittance of post-published data, this may give Applicants the chance to file earlier, and to pursue broader and more speculative claims in European patent applications, with the aim of later relying on the use of post-filing data to prove a technical effect, if necessary.  


You can read Roona's article and the full edition of the magazine here. 


Our offices


+44 20 7831 7929

Bedford House, John Street, London, WC1N 2BF, United Kingdom


+44 20 7831 7929

Suite 3.05, Platform, New Station Street, Leeds, LS1 4JB, United Kingdom


+44 20 7831 7929

Generator Hub, The Gallery, Kings Wharf, The Quay, Exeter, EX2 4AN, United Kingdom


+49 89 5150 5800

Widenmayerstr. 10, D-80538 München, Germany