Dependent claims are a key part of a claim set, although they are often given less attention than the independent claims. However, they can play a vital role in EPO opposition and appeal proceedings by providing useful fallback positions, particularly given that opponents cannot raise lack of clarity against the features of the granted claims. Moreover, it seems from a recent EPO Board of Appeal decision T 0878/23 that the dependent claims can also be crucial to the validity of an entire claim set and should perhaps be given more attention.
Background of decision T 0878/23
The case relates to a patent granted with an amended claim 1 directed towards a composition comprising a carrier material comprising a polysaccharide, at least one antioxidant and an amino acid combination selected from various specific combinations of two or three of cysteine, alanine, lysine and arginine. Claim 1 then specified that the amino acids lysine, alanine and arginine are each present in an amount of 8 to 20% based on total dry weight of the composition and cysteine is present in an amount of 2 to 10% based on the total dry weight of the composition. This feature was incorporated into claim 1 during prosecution. This meant that due to the recited combinations, the absolute minimum that could be present in claim 1 was 10 wt.% (e.g. 8 wt% cysteine + 2 wt% alanine).
However, granted claim 4 (from original claim 6) required that the total amino acid concentration be in the range from 3.5 to 36.5 wt.% based on the total dry weight of the composition. Clearly, this claim had not been updated following the amendment to claim 1, and it was now impossible for the composition to contain from 3.5 to < 10 wt.% of amino acids, since at least 10 wt.% total amino acid concentration was essential in claim 1. Therefore, part of the range of dependent claim 4 was incompatible with claim 1.
In view of this inconsistency, during the opposition proceedings the opponents raised a lack of sufficiency objection against claim 4 and argued that as it is impossible to carry out claim 4 over its full scope, the embodiment of claim 4 is insufficiently disclosed. The Opposition Division disagreed and stated in their Decision that: “the insufficiency objections are effectively inconsistencies between claims which amounts to disguised clarity issues not open for opposition”. Therefore, this inconsistency in the minimum amount of amino acids between independent claim 1 and dependent claim 4 was deemed simply a clarity issue, which is not a ground for opposition.
Board of Appeal’s decision on T 0878/23
However, on appeal, the Board of Appeal did not agree with the Opposition Division on this point, deeming claim 4 insufficient. In particular, the Board of Appeal stated that since the concentration ranges defined in claims 1 and 4 are mutually exclusive, i.e. incompatible, over a substantial part of their ranges, the skilled person cannot prepare the composition as defined in claim 4 across substantially the whole breadth claimed – even taking common general knowledge into account. The Board of Appeal further went on to explain that the composition of claim 4 has to take into account the concentration requirements of claim 1 as well, and that due to the incompatibility of these concentration requirements in claims 1 and 4 over a substantial portion of the range claimed, the skilled person cannot prepare for technical reasons a composition that fulfils the requirements across substantially the whole breadth of claim 4.
This brings us to another point which many readers will be thinking – why couldn’t claim 4 just be deleted? The answer is that the Patentee was, in the Board’s view, too late. While both of the Opponents had raised an insufficiency objection against claim 4 in their notices of opposition, the Patentee did not submit any requests deleting claim 4 in response. The Opposition Division agreed with the Patentee that the issue was one of clarity, not sufficiency, and so no requests were filed deleting claim 4 during opposition proceedings or in the Patentee’s statement of grounds of appeal. The Opponent who appealed the Opposition Division’s decision maintained their objection against claim 4 in their grounds of appeal.
Following the preliminary opinion of the Board of Appeal indicating that claim 4 lacked sufficiency (contrary to the Opposition Division’s decision), the Patentee did file claim requests where claim 4 was deleted. The admissibility of claim requests in EPO appeal proceedings is at the Board’s discretion. However, at this late stage of the proceedings, new claim requests are, in principle, not taken into account unless there are exceptional circumstances, justified with cogent reasons by the Patentee (Article 13(2) Rules of Procedure of the Boards of Appeal). The Board considered that “exceptional circumstances” did not apply, since claim 4 as granted had already been objected to under insufficiency in the notices of opposition, and so this objection did not come as a surprise in the appeal proceedings. The Board of Appeal indicated that the Patentee should have filed the auxiliary requests (with deleted claim 4) at the latest with their reply to the appellant’s appeal, and therefore declined to admit the new requests into proceedings. As a result, the patent was revoked.
Take home points to consider
This decision provides us with several important points to consider both when prosecuting an application and during opposition and appeal proceedings. Firstly, making sure all dependent claims are narrower embodiments of the independent claim is crucial to avoid the sort of inconsistency identified above from arising. When independent claims are narrowed during prosecution, it should be checked whether any dependent claims need to be updated as a result.
Another point to consider is the interplay between Articles 83 (sufficiency) and 84 (clarity) EPC. Because lack of clarity is not a ground of opposition against the granted claims, it is common for opponents to argue a lack of sufficiency and for the patentee to argue in response that it is a matter of clarity not sufficiency. In particular, it is common for patentees to dismiss alleged inconsistencies between the claims as (at most) a matter of clarity rather than sufficiency. It seems following T 0878/23, however, that lack of sufficiency objections against dependent claims should perhaps be taken more seriously. In particular, when those dependent claims contain an area that doesn’t fall within the scope of claim 1, the claim may be vulnerable to being deemed insufficient if this decision is followed.
The Board in T 0878/23 emphasised that a ‘substantial portion’ of the range of claim 4 was incompatible with claim 1 and this seems to have contributed to the finding of insufficiency. At the moment, it is unclear how much of the dependent claim needs to be incompatible with the independent claim for it to be a ‘substantial portion’ that cannot be performed. Perhaps future case law will shed more light on this, but for now it seems the best course of action when facing this sort of objection is to consider limiting dependent claims with incompatible areas to ensure that they fall entirely within the scope of the independent claim, or simply deleting the incompatible dependent claims.
Perhaps the most important take home point is that claim requests should be filed as early as possible in EPO opposition proceedings to have the best chance of being admitted into proceedings. Admissibility of requests at the appeal stage is at the Board’s discretion, and it can be difficult to show that there are “exceptional circumstances” that justify the admittance of a request filed after the Board’s provisional opinion has issued. Even if an objection raised in a notice of opposition seems relatively minor, it is advisable to address it by means of one or more auxiliary claim requests early on. If a lack of sufficiency objection is raised against a dependent claim, amendment or deletion of the objected claim early on (at least in an auxiliary request) will give the best chance of having room to manoeuvre later on if the dependent claim does end up being held insufficient.
