Policing the Extent of Opposition: T 1486/23 on Unopposed Claims and Amendments
Board 3.4.01 confirms that independent claims falling outside the original extent of opposition can only be examined for compliance with the EPC to the extent of their amendments, shielding them from delayed validity attacks.
Independent claims that fall outside the original extent of an opposition can only be examined for compliance with the EPC to the extent of their amendments, even when they are modified to incorporate features from opposed claims.
The unyielding grammatical error
The patent at issue, EP 16196998.5, concerned a replaceable insert for an ophthalmological medical device for aspirating fluid. During the opposition proceedings, the proprietor amended claim 1 to specify that the insert features a seal arranged such that it "auf der Unterdruckseite der Folie derart umschließt" (encloses on the vacuum side of the film in such a way).
The Technical Board of Appeal found this grammatically flawed formulation fatal under Article 84 EPC. Because of the missing object, it was impossible to determine whether the seal enclosed the film itself, the half-shell, the vacuum area, the replaceable insert, or the counterpart in the medical device. The proprietor argued that the skilled person would understand the seal's function was to hermetically close the vacuum area, making the exact physical arrangement secondary. The Board rejected this, noting that the claim explicitly defined an arrangement where the seal encloses an object, and the grammatical error made it impossible to determine which embodiments fell within the scope of protection (reasons 5).
Even when the proprietor corrected the grammar in an auxiliary request to state that the seal encloses the film ("die Folie derart umschließt"), the Board held the definition contradictory. It was unclear how the seal could simultaneously be arranged outside the film to enclose it and be located on the vacuum side of the film (reasons 11).
The unopposed fallback claims
Faced with these clarity objections, the proprietor filed a new auxiliary request at 12:08 during the oral proceedings, deleting the problematic claims 1 and 2 entirely. The new independent claims 5 and 6 corresponded to granted claims 11 and 12.
Crucially, the opponent had originally filed a limited opposition that did not include granted claims 11 and 12. The opponent nevertheless argued that because these claims were newly introduced into the proceedings as independent claims, they should be fully examined for novelty and inventive step (a creative but ultimately unsuccessful procedural maneuver).
Policing the extent of opposition
The panel systematically dismantled the opponent's attempt to broaden the proceedings. For claim 5, which corresponded to granted dependent claim 11, the opponent relied on the exception established in G 0009/91, which allows examination of unopposed dependent claims if their validity is prima facie in doubt based on available information. The Board rejected this, noting that the specific feature of a "Füllstands-Sensor" (fill-level sensor) was not prima facie in doubt based on the prior art cited against the opposed claims. The opponent's reference to a pressure regulator in document D1 was insufficient to cast doubt on the validity of the fill-level sensor feature without further investigation (reasons 36–37).
The situation for claim 6 was even more restrictive. Granted claim 12 was an independent claim directed to a device with a receptacle for an insert according to claims 1 to 11. Because the proprietor had amended the referenced claims, claim 12 had to be adapted to explicitly incorporate the subject matter of granted claim 1. The opponent argued this adaptation opened the door to a full validity attack.
The Board firmly disagreed. While acknowledging that an unopposed independent claim cannot remain unamended if it references an opposed and amended claim, the panel held that such adaptations only trigger an examination for compliance with Article 84 EPC and Article 123 EPC concerning the amendments themselves. Because the opponent's novelty and inventive step objections did not arise from the amendments but would have applied equally to the broader granted claim 12, they were dismissed without consideration (reasons 52–53).
Practical implications
The decision in T 1486/23 reinforces the absolute boundary of the extent of opposition. When drafting a notice of opposition, practitioners must explicitly oppose all independent claims and any dependent claims containing significant fallback features (such as the fill-level sensor in this case).
If a claim is left unopposed, an opponent cannot rely on the proprietor's subsequent procedural cleanup to launch a delayed novelty or inventive step attack. Unless the narrow G 0009/91 exception applies, or the amendments themselves introduce a new deficiency, the unopposed subject matter remains shielded from substantive review. Furthermore, the case serves as a strict warning on claim drafting during prosecution. A grammatical error that leaves the physical relationship between components ambiguous will not be saved by functional language or the description if the resulting claim creates a spatial contradiction.
Sources
Further Reading
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