b) Proper exercise of discretion 

It is established case law that, on appeal against a decision taken by a department of first instance in exercise of its discretion, it is not for the board to review all the facts and circumstances of the case as if it were in that department's place and decide whether or not it would have exercised discretion in the same way. If the EPC requires that a department of first instance exercise discretion in certain circumstances, that department should have a certain degree of freedom to do so without interference from the boards. They should overrule the way in which it exercised its discretion in reaching a decision in a particular case only if they conclude that it did so in accordance with the wrong principles, without taking the right principles into account or in an arbitrary or unreasonable way, thereby exceeding the proper limits of its discretion (on this point, see, in particular, G 7/93, OJ 1994, 775, and T 640/91, OJ 1994, 918, where the board found that the department of first instance had exercised its discretion unreasonably and that this amounted to a substantial procedural violation).

Although G 7/93 was concerned with a specific situation, namely an examining division's refusal to admit amendments after issuing a communication under R. 51(6) EPC 1973, the boards have applied the criteria established there to their review of other discretionary decisions of the departments of first instance (T 820/14, see also T 858/17). For instance, the same approach has been taken to reviewing opposition division decisions on the admission of late-filed submissions (T 1209/05, T 1652/08, T 902/09, T 1253/09, T 544/12, T 1882/13).

In several decisions, e.g. T 1614/07, T 849/08, T 1788/12, T 1643/11, T 89/15, the boards have cited one or both of G 7/93 and T 640/91 when reviewing whether the department of first instance exercised its discretion properly.

In T 820/14 the board pointed out that so long as departments of first instance had exercised their discretion properly, the boards as a rule should not overrule their decisions and substitute their own discretion for that exercised at first instance. That applied regardless of whether not they ultimately decided to admit the previously refused submissions, uphold the refusal to admit them on different grounds or remit the case to the department of first instance and give it an opportunity to exercise its discretion anew. By the same token, however, the case law established in G 7/93 could not be interpreted as imposing on the boards any duty to uphold a proper exercise of discretion at first instance.