In T 208/88 date: 1990-02-28 (OJ 1992, 22) the board held that taking a different line from an isolated appeal decision ‒ as opposed to established board of appeal case law ‒ could not be regarded as a substantial procedural violation.
In T 494/07 the board held that if two apparently similar case constellations were decided differently, this could at most be regarded as an error of judgment. In the case at issue, the board held that not following an earlier board decision did not constitute a substantial procedural violation.
In T 875/98 the board noted that the Convention did not contain any rule of procedure which imposed on an opposition division an obligation to abide by a decision in a different case. It held that a single decision did not establish a "case law" which had to be adhered to in another opposition case, even if the subject‑matter of the two respective cases was closely related.