Excluding a technical feature is not inventive without evidence of a technical effect (T 1865/22)

The recent Board of Appeal decision in T 1865/22 considered the inventive step of a composition where the only distinguishing feature was a lower concentration of a component compared to the closest prior art. The prior art taught that higher concentrations of this component were advantageous. The Board of Appeal found that simply excluding a technical feature disclosed as essential or advantageous in the prior art cannot in itself establish inventive step in absence of evidence showing that a comparable technical effect to the prior art can still be achieved. G 2/21 was mentioned but not directly applied in the case given that the patentee's evidence of the invention's technical effects was considered late-filed. 

Inventive step at the EPO: The problem-solution approach and technical effects 

The assessment of inventive step at the EPO follows the problem-solution approach, which requires identification of the closest prior art, the objective technical problem to be solved, and an assessment of whether the claimed solution would have been obvious to the skilled person. The problem-solution places heavy emphasis on the problem to be solved by the invention in view of the closest prior art. The identity of the closest prior art, and the technical effect of the invention view of the closest prior art, are therefore be highly influential to the outcome of an EPO inventive step analysis. 

In need of paint removal

The Enlarged Board of Appeal (EBA) decision in G 2/21 considered the question of whether post-filed evidence can be used to support a technical effect of an invention view of the closest prior art. The EBA ordered that: "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."

Since G 2/21, the Boards of Appeal have generally interpreted the EBA order to mean that the application as filed does not need to explicitly mention the technical effect of the invention in view of the closest prior art, or to provide experimental evidence of it. As interpreted by T 0116/18, G 2/21 merely requires the purported technical effect to be "conceptually comprised by the broadest technical teaching of the application as filed" (T 0116/18, r.11.10). Accordingly, it may be "sufficient that the skilled person, having the common general knowledge in mind, and based on the application as filed, recognises that said effect is necessarily relevant to the claimed subject-matter." (T 0116/18, r.11.10). However, as clarified in later decisions such as T 1994/22, mere broad sweeping statements about providing "a quality product" are not sufficient to encompass and embody specific undisclosed technical effects.

Case Background

The case in T 1865/22 related to EP 3374443, owned by Atotech GmbH. The patent was directed to a non-aqueous stripping composition for removing organic coatings, such as epoxy resin and paint, from surfaces. The patent was opposed by Chemetall GmbH. The Opposition Division (OD) maintained the patent in amended form, and the Opponent appealed this decision.

On appeal, the claimed stripping composition was specified as comprising three components: a  solvent, co-solvent and a pH-active agent. The parties accepted that the only difference between the claimed composition and the composition disclosed by the closest prior art was the concentration of the co-solvent component. In the prior art, the co-solvent was described as 25% by weight. The claimed composition specified a co-solvent 2-20% by weight. The central question for the Board of Appeal was whether the claimed composition, differing only from the prior art by its lower co-solvent concentration, involved an inventive step.

Evidence of a technical effect? 

Critically, the application as filed did not mention any technical effects associated with the lower concentration of solvent. In the absence of any established technical effect for the distinguishing feature, the Board of Appeal thus formulated the objective technical problem as "to provide an alternative stripping composition" (r.4.3).

The Patentee argued that the skilled person would not have reduced the amount of the coupling agent (monoethylene glycol) in the prior art example because, according to the prior art disclosure, high concentrations of this component were essential for appropriate tolerance to water. In other words, the Patentee argued that the prior art taught away from the claimed invention. This argument had convinced the Opposition Division to acknowledge inventive step.

In contrast to the OD, however, the Board of Appeal did not find the Patentee's argument convincing. The Board of Appeal particularly found that arbitrarily varying the concentrations of components in a composition, including changing the concentration of one component in favour or to the detriment of others, is routine for the skilled person and does not involve an inventive step (r.5.1). The Board of Appeal concluded that "[t]he mere fact that claimed subject-matter excludes a technical feature [...] disclosed in the closest prior art as being essential or advantageous for a technical effect [...] cannot in itself establish the existence of an inventive step. Rather [...] it must be shown that the claimed subject-matter achieves said technical effect to an extent comparable to that of the closest prior art, even without this feature. Without such proof, the claimed subject-matter merely results in an obvious deterioration of the technical effect described in the closest prior art." (r.5.3). 

Following this reasoning, the Board of Appeal concluded that the claimed subject-matter lacked inventive step over the prior art and revoked the patent. 

Late filed evidence and G 2/21

At oral proceedings, the Patentee attempted to argued that the lower concentration of co-solvent specified in the claim was a distinguishing feature that resulted in a number of technical effects, such as a lower viscosity. Importantly, however, these submissions were not admitted to proceedings. The Board of Appeal considered the submissions to be amendments to the Patentee's appeal case and that allowing the submissions would be contrary to procedural economy (Articles 13(1) and 13(2) RPBA). 

Consequently, the way in which G 2/21 should be applied to the facts of the case was not considered by the Board of Appeal. The decision made only a brief reference to G 2/21, with the Board of Appeal merely noting that the application as filed did not mention anything about a reduction in viscosity. For the Board of Appeal, this raised the issue of "whether the respondent can rely on these effects at all for the assessment of inventive step" (r.9.2).

Final thoughts

The decision in T 1865/22 highlights the importance of providing evidence to support inventive step when claiming compositions or devices that omit features previously described as essential in the prior art. T 1865/22 also aligns with the established case law on arbitrarily selecting parameter ranges, reinforcing that merely changing the concentration of components without an associated technical effect will generally be considered obvious. As the Board of Appeal emphasised, the problem-solution approach requires that the distinction between the claimed invention and the prior art leads to a non-obvious technical effect. Interestedly, the patent in question in the present case was a European originating case. One might have expected the lack of focus on the technical problem in the application as filed to be a consequence of US-style drafting. 

In cases where the claimed invention might involve excluding a feature described as advantageous in the prior art, T 1865/22 thus serves as a reminder to establish clear technical effects associated with this exclusion at an early stage in the proceedings, and to provide adequate support for such effects in the application as filed. The challenge for establishing inventive step in the European patent system is anticipating which features of the invention will be those necessary to distinguish from the closest prior art, given that the closest prior art may not become known until after the application has been filed. In some cases, the closest prior art may not be known to the patentee until the granted patent is challenged by a third party. Whilst G 2/21 provides patentees with some leeway in these situations, T 1865/22 is a reminder that the earlier you can identify and provide evidence of your technical effect, the better.