Sufficiency at the EPO: two recent cases
Two recent Board of Appeal decisions illustrate the two sides of Article 83. One patent survived, the other did not.
Insufficiency under Article 83 of the European Patent Convention is often a twofold question. Can a person skilled in the art understand the claimed invention and put it into practice based on the presentation given in the patent application? And is the technical effect of the invention achieved in all possible embodiments that fall within the scope of the claim? A patent may describe one workable embodiment in considerable detail and still be insufficient if the claim extends to embodiments for which the promised result cannot be achieved.
Sufficiency is assessed from the application as a whole, including the description, claims and drawings, together with the skilled person’s common general knowledge. If the answer to either of the questions posed above is no, then the invention has not been disclosed sufficiently well.
T 0879/24: could the skilled person understand what the claim required?
The patent in T 0879/24 related to anti-icing systems for wind turbine blades. The invention involved determining an icing factor and selecting heating zones to be activated in response to the severity of an icing event.
The opponent’s sufficiency attack focused on a particular claim feature which specified determination of heating zones by “identifying one or more heating zones that provides a greater aerodynamic performance based on the icing factor”.
The Opposition Division considered it possible that this feature could mean that the greater aerodynamic performance depended on the icing factor. The application did not explain how the icing factor could possibly influence the aerodynamic performance of a heating zone. The Opposition Division therefore concluded that the skilled person could not implement the claimed feature and revoked the patent for insufficiency.
However, the proprietor proposed a different reading (which, presumably, was the meaning which had originally been intended). The phrase “based on the icing factor” referred to the identification of the heating zones. The application text explained that the icing factor indicated the severity of the icing event, and the controller used it to select zones whose heating would make the greatest contribution to aerodynamic performance.
The Appeal Board accepted the proprietor’s interpretation. It considered both readings linguistically possible, but only the proprietor’s reading made technical sense. Aerodynamic performance was essentially associated with the blade geometry, while icing reduced that performance. Under this correct interpretation, the skilled person understood from the text what the invention required and how to implement it.
T 1409/23: was the technical effect achieved throughout the claim scope?
Decision T 1409/23 concerned a microorganism identification method using MALDI-TOF mass spectrometry. Claim 1 required a sample containing microorganisms to be analyzed, a mass-to-charge ratio of a peak derived from a marker protein to be read, and the serovar of Salmonella bacteria to be identified on that basis. At least one of two proteins, S8 and peptidylprolyl isomerase, was used as the marker protein.
The Opposition Division had treated the claim as intrinsically limited to those Salmonella strains that could in fact be identified by peaks corresponding to those marker proteins. Under this interpretation, embodiments for which the selected marker did not permit reliable identification simply fell outside the claim. The patent was therefore considered sufficient.
The opponent challenged that view in the appeal process. The claim did not explicitly limit the method to the disclosed serovars, strains or uniquely identifying peaks. It extended to the identification of Salmonella serovars generally by using at least one of the two stated marker proteins. The key question was therefore not whether the patent gave the skilled person one intelligible example. It was whether the claimed identification could actually be carried in all serovars that the claim covered.
The proprietor argued that the skilled reader, considering the patent as a whole, would understand the claim as limited to serovars for which reliable identification was possible. The Board of Appeal rejected this implicit restriction. In its view, this proposed “self-limitation” amounted to reading unclaimed restrictions from selected embodiments into a broader claim.
Drafting implications
If a phrase can attach grammatically to two different parts of a sentence, as in T 0879/24, it is safest to state the dependency carefully. “Identifying, based on the icing factor, one or more heating zones whose activation improves aerodynamic performance” would have made the intended relationship harder to misunderstand.
Where an invention has been demonstrated only for particular species, ranges or operating conditions as in T 1409/23, the drafter must ask whether the broader functional result is credibly possible in all embodiments that the claim covers. If not, the important boundaries should be discussed at least in the description, so that the claim can be narrowed in the future, if necessary.
G 1/24 and sufficiency
Both cases also contain an interesting procedural curiosity. The proprietors referred to G 1/24 when arguing that the claim should be interpreted in light of the description. However, the order in G 1/24 is expressly framed for the assessment of patentability under Articles 52 to 57 EPC. It does not state a rule for Article 83. The case law on Article 83 already requires sufficiency to be assessed on the basis of the application as a whole, including the description and drawings. Nevertheless, neither Board dismissed the G 1/24 references as irrelevant because the dispute concerned sufficiency. In T 0879/24, the Board expressly relied on G 1/24 when interpreting the disputed feature and rejected the opponent’s narrower account of that decision. In T 1409/23, the proprietor likewise invoked G 1/24, but the Board rejected the proposed self-limiting interpretation.
