In T 1225/13 the Board of Appeal adopted a claim interpretation that was only apparent to the parties from the written decision. This new interpretation lead the Board of Appeal to conclude that the claim lacked an inventive step. R 0003/15 ruled that this was a violation of Article 113.

Article 113 of the EPC states that decisions of the EPO may only be based on grounds or evidence on which the parties have had an opportunity to comment. Case law has confirmed that "grounds or evidence" is to be interpreted rather broadly meaning "the legal and factual reasons leading to refusal of the application". Some further case law has established that a party should not be "taken by surprise" by the reasons of a decision that refer to unknown grounds or evidence.

This case law was put to particular test in R 3/15 where it was discussed whether a new and surprising claim interpretation, which was only apparent from the written decision and not at the proceedings themselves, would constitute grounds or evidence on which the parties could not comment.

The Patentee filed a petition for review against the decision T 1225/13 as they alleged that the Board of Appeal (hereafter "the Board") construed a claim feature in a new way that led them to revoke the patent for lack of inventive step. This new construction, the Patentee further alleged, was not mentioned by the Board at the oral proceedings, and therefore constituted a surprise to the Patentee from the written decision.

The claim feature in question was "at all magnifications". Specifically, claim 1 related to a telescope in which a subjective field of view of the telescope of at least 22 degrees was guaranteed "for all magnifications". The public prior use of a particular telescope was prior art for claim 1. This telescope achieved a field of view of less than 22 degrees, but only for magnifications between 2 and 2.7.

The Board took the view that "all magnifications" did not mean every magnification. Rather, the Board considered "all magnifications" in claim 1 to mean all magnifications of the telescope with a magnification greater than fourfold. The Patent was maintained during the Opposition procedure according to an auxiliary request in which an early clause of claim 1 was amended to specify that an inverting system of the telescope had an adjustable magnification greater than four times.

Therefore, the Board construed the claim feature to be only those magnifications, effectively using an early claim feature to limit a later one. This in fact removed small magnifications from the set of "all", and restricted the magnifications of claim 1 to those that were anticipated by the public prior use. The Board then said that the technical effect was to achieve a subjective field of vision of at least 22 degrees in those magnifications, and that the objective technical problem was to provide an alternate embodiment of the telescope.

The Enlarged Board of Appeal (the "Enlarged Board") agreed with the Patentee that the Board did not make this construction apparent during the oral proceedings. As a consequence, the reasons accompanying the written decision were of surprise to the Patentee who also could not therefore have commented on this new (inventive step) argument by the Board at the oral proceedings themselves. The Enlarged Board therefore found that the Patentee's right to be heard was violated.

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