In T 12/03 the board stated that a substantial procedural violation is an objective deficiency in the procedure in the sense that the rules of procedure have not been applied in the manner prescribed by the Convention. According to J 6/79 (OJ 1980, 225), the giving of incorrect information by the EPO about the rules of procedure, which, if followed by the applicant, could lead to the same consequences as the incorrect application of those rules, could also be considered as lying within the scope of a "procedural violation". In T 690/06 the board held that an error of judgment on substantive issues by the examining division did not constitute a "procedural" violation (see also T 698/11, T 658/12). See also in this chapter V.A.9.5.8.

In T 990/91 the board held that the lack of opportunity to reply to a new argument from the examining division in its decision to refuse the application that was supererogatory and incidental could not be considered to be a procedural violation (see also T 1085/06).

In T 68/16 the board noted that the opposition division had not used the problem-solution approach. The board stated that this fact in itself did not constitute a substantial procedural violation. The problem-solution approach is not enshrined in the EPC and its use is not mandatory. The board agreed that, as a rule, a division that does not use the problem-solution approach should indicate its reasons for doing so, if only to dispel the impression that it acts arbitrarily. However, the Guidelines for Examination only state that any "deviation from this approach should be exceptional" and do not require a justification (see Guidelines G‑VII, 5). Consequently, the board found that a division that, in an exceptional situation, chooses not to use the problem-solution approach and not to explain its choice does not commit a substantial procedural violation.