T1688/20 – New rules in the numbers game?


Numerical ranges appear frequently in patent claims, across many different fields. For example, the components of a pharmaceutical formulation, the parameters of a manufacturing process, or the dimensions of a device or piece of machinery. In this recent decision, T1688/20, the Board of Appeal of the EPO has taken a diverging approach to the novelty of a numerical subrange.

The relevant patent claimed a particular “rotary atomizing electrostatic applicator”, or machine for spray painting cars, characterised by a particular twist angle of the air discharged from the applicator, which was “56 degrees or more and 59 degrees or less” in the direction opposite to another rotating part of the machine. The Opposition Division of the EPO (OD) had found that the numerical range feature was anticipated by a document disclosing a twist angle of 50 degrees or more and 60 degrees or less, in particular substantially 55 degrees. In its assessment of novelty, the OD applied the test in the previous case law of the Board of Appeal (T198/84) and concluded that none of the following criteria were met by the sub-range:

  1. the selected sub-range is narrow compared to the known range;
  2. the selected sub-range is sufficiently far removed from any specific examples disclosed in the prior art and from the end-points of the known range; and
  3. the selected range is not an arbitrary specimen of the prior art, i.e. not a mere embodiment of the prior art, but another invention.

On appeal, the Board noted that criterion (c) of the test applied by the OD is required for inventive step, rather than novelty, as stated in the Guidelines for Examination (G-VI, 8(ii)). As to criteria (a) and (b), the Board was not convinced that these tests, referring to “narrow” and “sufficiently far removed” are objective, solid and consistent when it comes to assessing novelty of a subrange. Rather, such terms are open to a broad interpretation.

The Board concluded that it was not necessary to adopt the tests in (a) and (b) to assess novelty and eschewed the test set out in previous case law and the current Guidelines for Examination. Instead the Board referred to the “Gold Standard” test, set out in G3/89, G11/91 and G2/10, to consider:

“what a skilled person would have derived directly and unambiguously, using common general knowledge from the description, claims and drawings of the European patent application, seen objectively and relative to the date of filing”.

The result was a finding that the claimed subrange of 56°≤ and ≤59° was novel (and inventive) in view of the prior broader disclosure of 50°≤ and ≤60°.

The Board drew from the case law on added matter that no test or list of criteria should lead to a different result than application of the Gold Standard. It is not necessary to apply any supporting test or criteria in reaching an assessment of whether the prior art directly and unambiguously discloses the invention claimed. In this case, the Board found that it did not. The Board was not convinced by the opponent’s arguments and found that:

  1. it is not the case that an angle value somewhere within the disclosed range can be considered as directly and unambiguously disclosed, this also applies where the relevant value is adjacent to a boundary value;
  2. with regard to error margins and rounding off, the skilled person would not consider that different nominal values correspond. The opponent’s argument that “55 degrees or 60 degrees disclosed by [the prior art] covers the disclosure of a value of 55.4 degrees or 59.5 degrees respectively, while the claimed values of 56 and 59 degrees also protect values of 55.5 and 59.4 degrees respectively” therefore failed.
Hidden numbers

The approach in England and Wales, as summarised by Christopher Clarke LJ in Smith & Nephew v Convatec[1], is that “figures, no less than words, may take their meaning from the context in which they are used”. More recently in Regen v Estar[2], where the Actavis questions on infringement under the doctrine of equivalents were applied to a claim with a numerical limit, HHJ Hacon reminded patentees and would be infringers that claims containing numerical limits are not in a special category when it comes to assessing the claim scope.

A prime example of how such claims are assessed with regard to validity is Jushi v OCV[3], an action commenced before the Intellectual Property Enterprise Court (IPEC) for revocation of a patent which claimed a fibre glass composition. The range of each of the constituents in a piece of prior art (“Neely”) either fell within or overlapped the corresponding ranges of various claims of the patent in suit. Furthermore, the ratio of two components of the fibre glass was stated in Neely to be ≤ 2. The corresponding ratio of the patent was 2.14 and the patent also compared the favourable properties of the claimed composition with those described in Neely. In light of the comparison in the patent with Neely, the judge found that it was fair to assume the patentee did not intend for its claims to cover the example of Neely, and therefore would not benefit from broadening as a result of whole number rounding. In relation to the overlapping ranges, the judge at first instance considered the approach in T 26/85 TOSHIBA/Thickness of Magnetic Layers and T 666/89 UNILEVER/Washing Composition and asked whether the skilled person reading the prior art document would “seriously contemplate” applying the teaching of the prior art in the area of overlap.

On appeal[4], the Court also rejected the argument that, based on using whole number rounding, the ratio in Neely would fall within the ≤ 2 ratio specified in the claim and anticipate the patent. The Court found an apparent intention of the patentee to contrast the invention with the disclosure in Neely and the claim was interpreted by the Court of Appeal as being “exact, and not meant to be broadened by whole number rounding”. However, the Court of Appeal expressed caution regarding the “serious contemplation” test, stating that “[i]t is only if the serious contemplation test is intended to relax the rigor of the general law of novelty that I would take issue with the EPO”. The Court, however, accepted the appellant’s submission that the serious contemplation test is no more than a way of distinguishing between matter which is properly regarded as hidden in the prior document and matter which is made available and disclosed. On that basis, the assessment is no different to that set out in Synthon’s Patent[5], which is to deprive patent of novelty:

“the matter relied upon as prior art must disclose subject-matter which, if performed, would necessarily result in an infringement of the patent”.

The Board’s “back to basics” assessment in T1688/20 appears to align with the English Court’s approach to interpreting claims with numerical limits, which is to focus on the simple question of whether the prior art discloses and enables the invention. There is no rule that assumes that there is an implicit disclosure that a skilled person may choose any value within a disclosed range.

A note on inventive step and the doctrine of equivalents

In relation to inventive step, the Board in T1688/20 was not convinced by the Opponent’s arguments concluding, inter alia, that “the technical effects due to the variations of the twist angle are recognisable in view of the comparative examples” and “[t]he influence on the coating efficiency and on the paint particle diameter in view of the different values of twist angle and under the same boundary conditions of air pressure and flow rate can be clearly recognised”. The Board further held that the selected sub-range was associated with technical effects which provide a purposive selection and therefore cannot be considered to be arbitrary. The Board was convinced that there was no hint in the prior art towards the narrower range.

The opponent had argued before the Board of Appeal that that the alleged effects of improving the coating efficiency are also achieved by twist angles outside the claimed range, such as 55 degrees. These facts might point in favour of a device with a twist angle of 55 degrees infringing the patent as an equivalent under English Patent law, following the test set out by the Supreme Court in Actavis v Lilly. However, in view of the overlap with the prior art, the alleged infringer could now expect to benefit from a Formstein defence (that the alleged infringer is merely practising the prior art). Only recently, in Vernacare v Moulded Fibre Products[6] Nicholas Caddick QC, sitting as a judge in the IPEC, found for the first time that the defendant was entitled to a Formstein defence.

Summing up

This case confirms that the “Gold Standard” test is king when it comes to assessing novelty for claims containing numerical ranges. Whilst other tests might support the analysis, the key question is what can be derived directly and unambiguously from the prior art. The Board of Appeal’s approach aligns with the analysis of the Court of Appeal in Jushi, which was conscious to ensure that the rigor of the law of novelty should not be relaxed by reference to other tests. The opponent’s arguments based on rounding and proximity of the boundaries of the range were not successful and, while context is important, the starting point is that a disclosure of a range is not a clear and unambiguous disclosure of every value within it. However, where the boundaries are close this will likely have implications in assessing the claim scope for the purposes of infringement.


[1] [2012] EWCA Civ 1638
[2][2019] EWHC 63
[3][2017] EWHC 171 (IPEC)
[4][2018] EWCA Civ 1416
[5][2006] RPC 10
[6][2022] EWHC 2197

Andrew Bowler


Chloe Dickson


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