a) Relationship between prima facie assessment and in-depth assessment 

According to established case law of the boards of appeal, a decisive criterion for admitting late-filed documents is their prima facie relevance, see e.g. T 1002/92, OJ 1995, 605; T 212/91, T 931/06, T 1883/12 and T 1511/14; for appeal proceedings, see chapter V.A.4.4.6 and in particular chapters V.A.4.1.2, V.A.4.4.6, V.A.4.5.7, V.A.4.5.8. and V.A.4.5.11.

Prima facie relevance is ascertained on the face of the facts, i.e. with little investigative effort, which reflects the need for procedural expediency in considering and admitting late-filed facts and evidence (T 1883/12).

In T 1348/16 the board considered that the opposition division, in admitting a document which it had found to be prima facie relevant and potentially prejudicial to the maintenance of the patent in suit, had based its decision on the right principles and that there was no reason to doubt that it had exercised its discretion in a reasonable way. This was not contradicted by the fact that a detailed analysis of the document later led the opposition division to conclude that it was actually not novelty-destroying and that another document represented the most relevant state of the art. Such an in-depth analysis was not part of the prima facie assessment of the relevance of a document.

In T 1525/17 the board observed that it was inherently contradictory to take late-filed documents as a basis for an in-depth examination of the patentability requirements, and so consider them as to their substance, yet at the same time declare them not admitted, as the opposition division had done in this case, having fully considered documents E5 and E6 in its thorough substantive assessment of inventive step. That assessment had not been referred to explicitly as a prima facie assessment of the documents' relevance; nor could it be regarded implicitly as a matter to be settled before dealing with their non-admission. The refusal to admit them therefore amounted to an erroneous exercise of discretion. See also T 1185/15 (necessary thorough analysis at odds with finding that document is not prima facie relevant) and T 346/16.