European Patents: How A Poorly Drafted Alternative Can Compromise Sufficiency Of Disclosure

In decision T 1186/24, the EPO Board of Appeal reiterated that a European patent claim covering multiple alternatives must enable each of them to be carried out across the entire claimed scope. A single alternative introduced by "or" can thus undermine a patent's validity if it is not sufficiently disclosed, as Charles-Henri Bertaux explains. 

During the appeal proceedings and in this decision (T 1186/24), the main legal issue concerns sufficiency of disclosure, specifically regarding the presence of the alternative "or" in claim 1 and the corresponding subject-matter. In particular, the question is whether each of the covered alternatives complies with the requirements of Article 83 of the European Patent Convention (EPC). 

Sufficiency of disclosure at the heart of the dispute

In this case, the Board of Appeal of the European Patent Office (EPO) ruled on the patentability of the invention defined in European patent No. 3 286 308, which relates to an enzymatic process for preparing a chemical compound or a mixture comprising said compound. 

At first instance, the grounds for opposition were lack of novelty, lack of inventive step, and lack of sufficiency of disclosure (Articles 100(a) EPC and 100(b) EPC) regarding the invention. In its decision, the Opposition Division rejected the invention as granted and auxiliary request 1 for lack of novelty and maintained the patent in an amended form (auxiliary request 2). Both parties filed an appeal: the patent proprietor requested that the decision be set aside and the patent maintained as granted or, alternatively, on the basis of four auxiliary requests; the opponent requested that the decision be set aside and the patent revoked in its entirety. 

Claim 1 of the main request relates, in essence, to a process for obtaining a compound – or a mixture comprising it – from a defined mixture of isomers via enzymatic conversion using a squalene-hopene cyclase/homofarnesol-ambrox cyclase (SHC/HAC) type enzyme (…). 

Interpretation of claims: what is the scope of the "or" alternative?

During the appeal proceedings and in this decision, the main legal issue concerned the sufficiency of disclosure, particularly regarding the wording of claim 1. 

In its decision, the Board held – in accordance with standard practice and contrary to the findings of the Opposition Division (decision, point 35) – that the term "or" defines two alternatives. Specifically, it considered that the two alternative products must be distinct; consequently, under the first alternative, the compound must be obtained as the sole reaction product, whereas under the second alternative, a mixture comprising said compound is obtained. 

The patent owner argued, in light of the description, that a person skilled in the art reading the claim would understand that the mention of the compound alone does not necessarily imply a result in which no other reaction products are formed. In other words, the owner maintains that this wording implies the production of said product as the major product of the process. 

The wording of the claim takes precedence for its interpretation

In its decision, the Board of Appeal reiterated and identified the primary element to be used when interpreting a claim: its wording. While the description may help resolve ambiguity, it cannot override clear claim language or deprive an expressly claimed alternative of its independent technical significance. 

The examples cited in the patent demonstrate that the compound cannot be obtained as the sole reaction product when using one of the suitable substrates. The Board noted that there is no reason to interpret claim 1 in a way that excludes embodiments falling within the ordinary meaning of the claim's wording simply because those embodiments might not be achievable. 

The Board observed that claim interpretation must begin with the wording of the claim itself. It notes in particular that, by using the term "or”, claim 1 sets out two distinct alternative results; these cannot reasonably be considered synonymous without depriving the second alternative of its independent meaning and thereby rendering the term "or" meaningless. 

Obtaining the compound "alone" is therefore not achieved if the result is a composition in which that compound is the major component. Another interesting point raised by the Board is that a reference to the compound alone does not imply that it is necessarily chemically pure. 

Article 83 EPC: The invention must be reproducible across the entire scope claimed

The Board reiterated that Article 83 EPC stipulates that the application must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. 

It recalled that a single working embodiment is insufficient if the claim is broader in scope: the invention must be capable of being carried out across the entire claimed scope without undue burden. Given that claim 1 encompasses embodiments in which the enzymatic conversion yields the compound as the sole reaction product, sufficiency of disclosure must also be assessed with regard to this embodiment. The patent’s examples consistently show the formation of a mixture and provide no teaching that would enable a person skilled in the art to avoid the formation of by-products and obtain said compound as the sole reaction product. 

Consequently, a person skilled in the art (in light of the patent’s disclosure and common general knowledge) would not be able to carry out the first variant of the claim. The auxiliary requests do not provide any element capable of remedying the aforementioned deficiency. 

Thus, the Board revokes the patent in its entirety, even if one of the alternatives appears, at first glance, to be sufficiently described. 

What are the implications for drafting European patent claims?

This decision confirms established case law regarding sufficiency of disclosure, particularly concerning alternatives. Specifically, if the invention comprises alternatives, each must be feasible without undue burden. The ruling reiterates, therefore, that the invention must be capable of being carried out across the entire claimed scope.