A decision by the EPO Board of Appeal has provided guidance to applicants looking to rely on an unusual parameter in a patent claim.
In decision T 0555/18, the Board found that the proprietor should bear the burden of proof to demonstrate that an unusual parameter is non-obvious. The opposed patent related to shrink film containing semi-crystalline polyamide. The proprietor was Cryovac, Inc.
Background
Unusual parameters are parameters not commonly used in the field of the invention[1]. An unusual parameter may:
- measure a property of the claimed product or process for which another generally recognised parameter is used in the field of the invention; or
- measure a property of the claimed product or process that was not measured before in the field of the invention.
The inclusion of an unusual parameter in a claim is not, in itself, objectionable. However, in inter-partes proceedings before the EPO, where an unusual parameter is used to distinguish the subject matter of a claim from the disclosure of the prior art and there is a strong presumption that the unusual parameter is inherently disclosed in the prior art, the burden of proof lies with the proprietor to demonstrate that the unusual parameter is not anticipated by the disclosure of the prior art (Board of Appeal decision T 131/03[2]). A similar principle is applied in ex-parte proceedings before the EPO: if an applicant fails to provide evidence to support that an unusual parameter distinguishes the claimed subject matter from the prior art, no benefit of the doubt can be accorded (Board of Appeal decision T 1764/06[3]).
The decision
In T 0555/18, the opponent filed an appeal against the decision of the opposition division to reject their opposition to European patent no. 2117839 (“the patent”). The opponent alleged that claim 1 of the patent lacked inventive step.
Claim 1 of the patent claimed a multilayer, heat-shrinkable film and contained the parameter “FTIR Transmission Absorbance Ratio: A1199/ A1170 ≤ 1.65”. The Board of Appeal (“the Board”) found this parameter to be the only distinguishing feature of claim 1 over the closest prior art document[4].
Contrary to the assertions of the patent proprietor, the Board considered the FTIR ratio to be an unusual parameter, because, while the parameter was not completely unknown, it was not generally used, in the field of the invention, in the specific form proposed in the claim[5].
The Board took the view that, when assessing the obviousness of an unusual parameter, a similar approach to that set out in T 131/03, concerning the novelty of unusual parameters, should be applied. More specifically, the Board stated that “once it has been established that it would be obvious for the skilled person to solve the underlying technical problem in ways that can be presumed to inherently lead to values within or close to the claimed range, it is the proprietor who should carry the burden of proof to demonstrate that implementing such solutions would not lead to the claimed parametrical range”. The Board considered this approach to be fair, to avoid proprietors benefiting from “the uncertainties created by the decision to define the invention in terms of an unusual parameter”[6].
In T 0555/18, the Board considered that it would be obvious for the skilled person, starting from the prior art, to contemplate films having high amounts of semi-crystalline polyamide. In the opinion of the Board, such films could strongly be presumed to exhibit the claimed FTIR ratio. Therefore, the burden of proof lay with the proprietor to demonstrate that such films would fall outside of the scope of claim 1[7].
The proprietor failed to provide any evidence that films having high amounts of semi-crystalline polyamide would possess an FTIR ratio outside the scope of claim 1. Accordingly, the proprietor failed to discharge the burden of proof and the subject matter of claim 1 was found to be obvious in light of the disclosure of the prior art7.
Practice points
To avoid proprietors or applicants benefiting from “the uncertainties created by the decision to define the invention in terms of an unusual parameter”, the EPO shifts the burden of proof to applicants and proprietors to demonstrate that unusual parameters are not obvious from, as well as not anticipated by, the prior art.
Applicants and proprietors attempting to distinguish their invention from the prior art by a parameter that could be considered unusual in the field of the invention, should be prepared to provide evidence to support that the parameter is both novel and non-obvious. Regarding obviousness, simply arguing that it is not impossible for products and processes made obvious by the prior art to fall outside of the parametrical range will not be sufficient to discharge the burden of proof7.
