T1977/22: Can claims defined by open-ended ranges ever be sufficiently disclosed?

The EPO’s Board of Appeal’s decision in T1977/22 provides an interesting review of the case law concerning the compatibility of whole range sufficiency and claims defined as a result to be achieved by use of an open-ended range. The Board concludes that open-ended ranges, which may include non-working embodiments, should be deemed sufficient and reproducible across the whole scope of the claim when it can be derived (at least implicitly) from the specification that the skilled person, when working the invention within the claimed structural and/or process features, would be able to achieve a number of different values across the open-ended range without undue burden.

Post-grant, a patent may be opposed, inter alia, on the ground that the invention is not disclosed in sufficient detail to allow a skilled person to carry it out. The bar applied by the EPO for assessing the minimum requirements for a sufficient disclosure often seems to be relatively low, meaning attacks on the grounds of sufficiency can be difficult to win. However, at first instance, the Opposition Division (OD) found that granted claim 1 of EP 3086872, which defined an inorganic composite oxide material exhibiting a minimum BET specific surface area after calcining at different temperatures for different durations of time, was insufficiently disclosed because of the absence of an upper limit resulted in claim 1 encompassing materials with surface areas significantly above the defined lower limit. According to the OD, the open-ended ranges meant that claim 1 covered materials having higher surface areas, which became accessible only after the filing date of the patent. The Board of Appeal disagreed.

Diverging case law?

During both the opposition and appeal proceedings, the Proprietor and Opponent cited a number of decisions that supported their respective positions. The Proprietor (Appellant) argued (citing T398/19) that open-ended claims do not give rise to an objection of insufficiency because the claim at issue is implicitly limited to the surface areas that can be actually obtained. The Opponent (Respondent) in turn argued (citing T1697/12 and T113/19) that the claim covered surface areas that are much higher than are practically available and consequently encompassed non-working embodiments, resulting in a fundamental lack of sufficiency. Both parties agreed that there was a divergence in the case law, with one body of decisions stating that open-ended ranges were unobjectionable under sufficiency, and another body that stated that they were inherently irreproducible and should be indirectly limited.

Upon review of the case law, the Board was disinclined to agree that there was divergence between previous Board decisions. The Board concluded that the principles and points of law were consistently applied across all of the decisions, with the different outcomes merely resulting from the facts of each case at issue. Indeed, it noted that none of the decisions reviewed state one way or the other that open-ended claims are inherently objectionable or unobjectionable. (A relief to all chemical Patent Attorneys and Applicants alike!)

Instead, the Board emphasised that all of the decisions implement the principle that a claim must be restricted to the breadth of the disclosure of the patent, with the burden to enable an open-ended range depending on how the invention is defined in the claim. In this respect, the Board noted two distinct situations:

• The element defined by an open-ended parameter is not restricted by structural and/or process features such that the result to be achieved via an open-ended range is supported by a few seemingly isolated and/or unrelated examples, without providing the skilled person without the requisite teaching of how to adjust parameters or adapt a process. As such, the open range is not limited to values achievable by a specific combination of features. The skilled person is therefore presented with an undue burden to provide different variants of the invention, and the patent would seemingly inherently fall foul of the sufficiency requirement which would likely only be rectified by a limitation to provide an upper boundary for the range;
• The element defined by an open-ended range is further restricted in the claim by structural and/or process features such that the skilled person is provided with sufficient information to adjust and modify the structural and/or process features to provide a number of working embodiments within the range with undue effort. In this case, the claim should be deemed to be conceptually limited by the technical solution demonstrated and therefore sufficiently reproduceable across its scope, as long as the claim recites the essential structural and/or process features.

The Board further noted that this approach does not unfairly hinder other parties from protecting further inventions aimed at increasing the parameters in question. In this regard, the Board emphasised that the above approach prevents a patent from being deemed sufficient unless the achievement of high parametric values is credible within the limitations provided by the (essential) structural and/or process features claimed. Thus, the scope of such a granted patent merely prevents further inventors from protecting inventions achieving indefinitely high parametric values with trivial or known technical solutions. In contrast, an inventor that finds an alternative solution for achieving a high parametric value would not be prohibited from seeking patent protection by an earlier patent as long as the technical solution used is different.

Decision

Turning to the case at hand, the Board found that the Opponent had failed to discharge its burden of demonstrating that the method disclosed in the patent would not enable the skilled person to modify the teaching and provide working embodiments falling across the claimed open-ended range. The argument that the presence of non-working embodiments results in insufficiency required a too-literal interpretation and thus was not consistent with the case law reviewed.

Nevertheless, the Board acknowledged that further analysis was required in response to the opponent and OD’s view that open-ended ranges inherently encompass non-working embodiments and, as such, cannot be enabled across their whole scope. Referring to its earlier conclusions, the Board stated that:

“The key criterion for determining whether the open-ended range is enabled over the whole scope of the claim is the availability of teachings showing that, by operating within the scope of certain (essential) structural and/or process features, the skilled person would be able to achieve different variants of the invention over the scope of the claim (i.e., different parametric values within the open-ended range) without undue effort. If that is the case and the claim defines these essential structural and/or process features, the open-ended range desideratum may in principle be considered to be reproducible over the whole scope of the claim”.

Therefore, the presence of non-working embodiments in and of itself does not deprive an open-ended range from being enabled and therefore sufficient.

In this regard, the Board noted that the patent provided two examples that showed that trivial adjustments to the components and/or concentrations of the oxide resulted in sufficient variation in the specific surface area such that the skilled person is provided with the necessary teaching to achieve different values across the open-ended range. As the concentrations and components of the oxide were claimed (notably using closed ranges), the claim comprised the essential features needed and was therefore sufficient.

Interestingly, the Board’s decision does make reference to the fact that they would have been willing to discuss whether certain method steps should have been incorporated into the claim as further essential features. However, the Board noted that during the opposition hearing, the Opponent explicitly rejected the position that method steps were required to provide sufficiency (and only relied on lack of enablement due to non-working embodiments). The Board therefore found no justification for introducing this argument ex-officio.

Final thoughts and practice points

As open-ended ranges are the bread and butter of many pharmaceutical and chemical patent applications, it is certainly good news to patentees that such ranges are not inherently insufficient. However, the continuous reference by the Board to the essential features within the claims appears to blur the line between sufficiency under Article 83 EPC (which is a ground of opposition) and clarity pursuant to Article 84 EPC (which is not). Whether this has broader implications for sufficiency objections against inventions not defined by open-ended ranges remains to be seen, but there does seem to be an opening based on this decision for presenting sufficiency objections based on a lack of essential features.

As a final point for practitioners, this decision clearly highlights that, when drafting claims with open-ended ranges at least, it would seem wise to pay particular attention towards providing proper basis for any potential structural and/or process features that may be deemed essential to enable the open range across its scope.

This article was prepared by Allie Tyson.