According to T 63/86 (OJ 1988, 224), where substantial amendments to the claims are proposed on appeal, which require substantial further examination, the case should be remitted to the examining division. In this way, the applicant's right to appeal to a department of second instance is maintained, both in relation to the exercise of discretion under R. 86(3) EPC 1973 (now R. 137(3) EPC), and in relation to the formal and substantive allowability of the amended claims. Several boards of appeal have applied this case law in their decisions; e.g. T 501/88, T 47/90 (OJ 1991, 486), T 332/05, T 637/06, T 1818/08 (all ex parte). This case law is also applicable to inter partes cases; see e.g. T 491/03, T 2287/08.

In T 746/91 the board applied the principles laid down in T 63/86 and remitted the case to the opposition division for it to examine and decide whether the claims should be admitted and, if so, whether they complied with the provisions of the EPC. The board took this view in the particular circumstances because the opposition proceedings had themselves been comparatively brief and had not involved the holding of oral proceedings. It had thus adhered to the principle whereby it should be established swiftly whether or not a patent can be maintained.

In T 125/94 the board remitted the case to the department of first instance because the amended claims had not only substantially changed the factual framework of the contested decision, but could also require a search in an additional classification unit to determine the closest prior art. In T 230/98, too, the subject-matter of the amended claims was most probably not covered by the search and had not yet been the subject of first-instance proceedings.

According to the board in T 1201/00, if a case is likely to have to be remitted to the opposition division for it to assess the unexamined issue of inventive step, a new auxiliary request first submitted during oral proceedings before the board designed to overcome an objection of lack of novelty compared with a cited document may exceptionally be admitted and also remitted to the opposition division for final novelty examination against that document if none of the requests that took precedence can be granted for lack of novelty. The need for the department of first instance to assess inventive step against all the cited prior art means that novelty examination against one cited document would not entail a significant delay in the opposition proceedings.

In T 908/07, the board held that a late-filed claim admitted in the exercise of the board's discretion mainly because the issues raised could be dealt with without adjournment of the oral proceedings, should not normally be remitted to the department of first-instance for examination in respect of the grounds for opposition on which the first instance decision was based. In T 111/98 the board held that the amendment of the claims in response to the citation of a new document during appeal proceedings was not as such a sufficient reason to remit the case to the department of first instance. Remittal remained at the discretion of the board (see also T 193/07).

In T 839/05, since the amendments were of a different nature for each auxiliary request, a possible consequence of remittal could have been further remittals on subsequent appeal proceedings, which would unduly lengthen the proceedings. Thus, with due consideration made for procedural economy and to avoid further delay, the board decided not to remit the case.