Contradictory claims, clarity and insufficiency: High stakes for patent applications

T 0878/23 concerned EP3317395, a Nestlé-owned patent that addressed a common challenge for the probiotic industry in keeping microorganisms viable in products with a long shelf life.

The patent, which was made up of several claims related to compositions that included specific combinations of amino acids, was challenged by Japanese milk company Morinaga Milk, as well as DSM-Firmenich, a global supplier of nutrition, health and beauty products.

Whilst the European Patent Office’s (EPO) Opposition Division upheld the patent, it did so only in an amended form, leading Morinaga Milk and Nestlé to appeal this decision.

The key issue on appeal was whether the original claims met the requirement of sufficiency of disclosure due to certain inconsistencies in the amino acid weight percentage calculations in the first and fourth claims, or whether this was simply an issue of clarity, and therefore not viable grounds for opposition.

Whilst novelty and inventiveness are key for patentability, a patent must also be practically usable, a concept known as ‘industrial applicability’. To meet this requirement, an application must disclose enough detail to allow a skilled person to make and use the invention without guesswork.

This principle is set out in Article 83 of the European Patent Convention (EPC), which requires “sufficiency of disclosure” in patent applications. 

According to the EPO’s general guidelines, this means that an invention’s description must disclose “any feature essential for carrying out the invention in sufficient detail to make it apparent to the skilled person how to put the invention into practice”, without “undue burden” or “needing inventive skill”.

Provided an applicant has explained their invention fully, they can receive a temporary monopoly on it. 

For further discussion on the concept of sufficiency, you can read our insight examining why sufficiency matters at the priority date here.

Article 84 EPC also requires claims to be clear, precise and supported by the description. The latter is particularly important given the aforementioned landmark decision in G1/24, which changed how claims are to be interpreted, and which now requires examiners and courts to consult the description and drawings, even when claims are not unclear or ambiguous.

Distinguishing between insufficiency and lack of clarity is important, primarily because clarity issues cannot be raised in opposition and revocation proceedings unless they result from post-grant amendments.

Insufficiency, however, is always a ground for opposition and revocation. If found to be valid, it can lead to a patent being cancelled and treated as if it never existed.

In Nestlé’s patent, the first claim (‘Claim 1’) defined a minimum amount of the amino acids lysine, alanine and arginine as in the range of 8-20 weight percent (wt.%). It also gave a minimum amount of cysteine in the range of 2-10 wt.%.

The fourth claim (‘Claim 4’), which was also dependent on Claim 1, defined the total amino acid concentration as being in the range of 3.5-36.5 wt. %.

In considering the case, the Board of Appeal calculated that any composition falling under Claim 1 must have a minimum total amino acid concentration of at least 10 wt.%, or possibly up to 16 wt.%, depending on the specific combination. On its own, this would comply with Article 83 EPC as sufficient disclosure.

The total amino acid concentration in Claim 4, however, directly contradicted the ranges in Claim 1, because the lower end of Claim 4 (3.5 wt.%) was incompatible with the minimum 10 wt.% required by Claim 1 as calculated by the Board of Appeal.

According to Nestlé, this incompatible language problem was merely a clarity issue falling under Article 84 EPC. As such, it was simply for the Board of Appeal to correct, and not grounds for opposition or revocation.

The Board of Appeal disagreed, finding that, whilst Claims 1 and 4 were clear and sufficient in isolation, they were also mutually exclusive over a substantial part of their ranges.

This meant that a skilled person would not be able to technically prepare a composition satisfying the full breadth across both claims, because the range from 3.5 wt.% to less than 10 wt.% was impossible to achieve whilst complying with Claim 1.

As such, the result of this contradiction was not a lack of clarity, but insufficiency, which ultimately led to revocation of the patent.

This decision creates a precedent for opposing mutually incompatible claims under Article 83 EPC, which could see more patents revoked on the grounds of insufficiency.

It is not enough for each claim in a set to be clear and precise; they must also be mutually supportive or coterminous (i.e. having the same boundaries or limits). 

As we await the outcome of G1/25, which will hopefully address the requirement of aligning patent descriptions with patent claims, T 0878/23 serves as a reminder of the importance of careful, consistent drafting – lest one’s patent is found contradictory and, ultimately, vulnerable to revocation.