The problem of being bound by an earlier board of appeal decision where a case is remitted also arises in connection with a subsequent appeal against the ensuing decision.
In a number of decisions, the boards have observed that they are bound by their own initial decision if a second appeal relating to the same subject-matter is brought before them (a "self-binding" effect, known by the German term Selbstbindung). The binding effect of the initial decision extends to all further findings made by the board in so far as they were decisive for the outcome of that decision and the facts have not changed (T 961/18; see also T 1545/08). However, the board can be bound only in so far as the facts are the same and only in so far as its legal assessment in the initial decision itself went (T 2337/16). However, they are not so bound where the facts underlying the initial decision have changed (Art. 111(2) EPC 1973) (T 21/89; see also T 153/93 and T 1545/08). This is often based on the argument that that board of appeal decisions are final and without appeal, so that no EPO body – not even boards of appeal – can take a new decision on facts which have already been decided. In T 690/91 the argument was that the same binding effect applied to any subsequent appeal proceedings since, according to Art. 111(1) EPC 1973, the board might exercise the same power as was within the competence of the department which was responsible for the decision appealed.
See also T 720/93 for the extent to which a board considered itself bound by an earlier board of appeal decision in the same case. Although the claim pending before the board represented different facts from in the first proceedings since it was a different type of claim and contained a number of different features, the board found some findings of the first decision binding for the second proceedings.
The board in T 736/16 had to rule on a second appeal brought by the appellant on the basis that it had no longer been open to the opposition division to examine compliance with Art. 123(3) EPC because the board had already settled that matter in relation to the same request when ruling on its first appeal in T 1909/12. The board agreed that both the opposition division and it itself were bound under Art. 111(2) EPC by the ratio decidendi in its decision on the first appeal (and, indeed, by those in R 3/14, another earlier decision issued in the same case). However, since it had not explicitly referred to Art. 123(3) EPC in either in the order or the reasons for that decision, it first had to ascertain whether it could be clearly inferred from any parts of the reasons that it had indeed already decided that the appellant's request met the requirements in that article. It concluded that it had not done so.
In T 449/15 the board had to compare the subject-matter of respective claim 1 of the main request decided upon in T 449/13 and of auxiliary requests 4 and 5 pending before the board for consideration in the second appeal proceedings. The amendments only amounted to an inclusion of redundant linguistic additions and merely represented cosmetic changes without any effect on the scope of the claims. Therefore, the board concluded that the amendments undertaken did not alter the subject-matter claimed in substance compared to the subject-matter finally decided upon in T 449/13, or the facts on which said decision was based. Consequently, the finding that the claimed subject-matter lacked an inventive step was res judicata. In this context, the board noted that there have also been other decisions in the jurisprudence of the boards of appeal in which the competent boards considered themselves as being prevented from deciding on an issue due to the principle of res judicata, even though the claims under consideration were not literally identical to the claims decided upon in the earlier decision (see e.g. T 1872/08, T 572/07, T 436/95).
On the binding effect of a final decision on the subject-matter of the parent application in proceedings relating to divisional applications, see chapter II.F.2.4.