If the way in which a department of first instance has exercised its discretion on a procedural matter is challenged in an appeal, it is not the function of a board of appeal to review all the facts and circumstances of the case as if it were in the place of the department of first instance, and to decide whether or not it would have exercised such discretion in the same way as the department of first instance. A board of appeal should only overrule the way in which a department of first instance has exercised its discretion if the board concludes it has done so according to the wrong principles, or without taking into account the right principles, or in an unreasonable way (T 640/91, OJ 1994, 918; see also T 182/88, OJ 1990, 287; T 986/93, OJ 1996, 215; T 237/96 and G 7/93, OJ 1994, 775, T 1119/05 and T 1707/07.
A board of appeal, when reviewing the opposition division's exercise of discretion under Art. 114(2) EPC, has the power to overrule a decision not to admit a late-filed ground of opposition, if the board concludes that the opposition division based its decision on manifestly incorrect technical assumptions or on an erroneous approach to applying said ground of opposition since this amounts to a misuse of the discretionary power under Art. 114(2) EPC (T 109/08).