In G 1/03, point 2.3.4 of the Reasons, the Enlarged Board held that, when anticipation was taken to be accidental, this meant that it appeared from the outset that the anticipation had nothing to do with the invention. Only if this was established could the disclaimer be allowable (see also order in G 1/03).
In T 500/00 the amendment was a disclaimer introduced by the appellant into claim 1 during the examining proceedings in response to an objection of lack of novelty based on prior art document D1. The question arose as to the requirements under which such a disclaimer might be allowable.
According to G 1/03 (OJ 2004, 413), a disclaimer may be allowable in order to restore novelty by delimiting a claim against an accidental anticipation under Art. 54(2) EPC 1973; thus the question that arose was whether or not the disclosure of D1 was accidental.
In the case in point, the claimed solution showed an overlap with the teaching of D1. D1 and the application in suit concerned the same technical field, had, except for the disclaimed component, identical compositions and related to the same purpose of sufficient curing. Moreover, the same technical problem underlay both the patent in suit and D1. Since the skilled person would consider D1 as suitable prior art to make the invention, confirmed by the reference to D1 in the original application, the disclosure of D1 could not be considered as being accidental within the meaning of G 1/03. Furthermore, since D1 related to the same technical effect as the patent in suit, and since its starting polymers to be cured were structurally identical to those used in the claimed process, D1 could be considered as a suitable starting point for assessing inventive step.
The appellant's position that transitional provisions should be provided for in G 1/03 for those applicants who had relied in good faith on the previous EPO patent practice at the time of making the disclaimer failed as well, as explained by the board. The principles laid down in G 1/03 were to be applied to the present case. Since the disclosure in D1 could not be considered as accidental within the meaning of G 1/03, the disclaimer was not allowable under Art. 123(2) EPC 1973.
The decision in T 14/01 concerned the allowability of a disclaimer aimed at removing an overlap with prior art in view of G 1/03. According to the board in this case, the allegation that a teaching extracted from prior art led away from the invention implied that the skilled person had taken this prior art into consideration. Yet for an anticipation to be accidental it was necessary that the skilled person would have never taken it into consideration. The board then decided that the prior art in question was not accidental in the sense of G 1/03, and that the disclaimer was not admissible.
In T 1049/99 the board concluded that, contrary to what the respondent (patent proprietor) claimed, the skilled person would have taken the teaching of document D21 into consideration when working on the invention in search of a solution to the technical problem defined by the respondent, using appropriate and relevant means to resolve his problem in the same technical field as that of the patent in suit. Moreover, contrary to the respondent's conclusions at the hearing, the board stressed that the fact that a document was difficult to find in published prior art or was difficult for the skilled person to access was not sufficient to justify the conclusion that it constituted an accidental anticipation.
In T 217/03, on the issue of whether document D1 was an accidental anticipation, the board stated that D1 did not deal explicitly with the technical problem underlying the claimed invention. However, that was not decisive for accepting D1 as an accidental anticipation. The board concluded that D1 related to the same general technical field as that of the subject-matter of claim 10 and was not from a technical point of view so unrelated and remote that the person skilled in the art would never have taken it into consideration when working on the invention (see G 1/03, OJ 2004, 413, point 2.2.2 of the Reasons). Thus the disclosure of D1 could not be considered to constitute an accidental anticipation. Therefore the disclaimer in claim 10 did not fulfil the conditions required to render it admissible.
In T 788/05, the disclaimer, which was not disclosed in the application as filed (concerning Vascular catheter), was introduced by the appellant during the examination procedure with the purpose of establishing the novelty of the claimed subject-matter with respect to D1, which was then considered as a prior art document relevant under Art. 54(3) EPC 1973. In the present case the relevant prior art was represented by documents D1 and D5. To be allowable the disclaimer had to fulfil the conditions in relation to both documents. As far as D1 was concerned, the disclaimer appeared to be appropriate. D5 represented the state of the art under Art. 54(2) EPC 1973. As D5 was not state of the art under Art. 54(3) and (4) EPC 1973 and was not an accidental disclosure, the disclaimer would only be allowable if it did not add subject-matter within the meaning of Art. 123(2) EPC 1973, i.e. if the disclaimer did not become relevant for the assessment of inventive step. Going into details, the board concluded that the subject-matter of claim 1 of the main and the first auxiliary requests was not acceptable under Art. 123(2) EPC 1973.
Other decisions too have had to establish whether or not an anticipation was accidental. In T 717/99, for example, the board did not agree with the opponent's conclusion that the anticipation was not accidental. In T 1086/99, T 584/01, T 506/02, T 285/00, T 134/01 (field of pharmaceuticals, same illness; findings summarised by the board in T 1911/08, in which account was also taken of T 739/01, T 580/01 and T 639/01), T 1146/01 (on comparative examples of a prior art document providing a teaching not to be followed) the boards ruled that the anticipation was not accidental and that the disclaimers were therefore inadmissible.
In T 285/03 the board found that the interpretation offered by the appellant amounted to a disclaimer although it was not phrased in the usual form. However, that disclaimer was not based on a particular prior art disclosure, whether accidental or not, but tried to delimit the claim against any potential prior art disclosure, contrary to the principles set out in G 1/03.