Refusal To Hear Witnesses on Alleged Public Prior Use: EPO Reinforces the Duty To Take Decisive Evidence (T 1113/24)

Originally posted at V.O.’s website, a contribution by Peter de Lange

In T 1113/24 (Technical Board of Appeal 3.2.07, 9 December 2025) the Board set aside an opposition decision because the Opposition Division (OD) rejected an alleged public prior use without hearing two witnesses offered to prove contested, outcome-determinative facts. The decision is a procedural reminder that an EPO department may not refuse relevant witness evidence by pre-judging its probative value.

Background 

The opposition against EP 3 120 940 was based, among other grounds, on an alleged public prior use (“Adelholzener”). The opponent relied on a set of documents (including technical drawings and diagrams) and requested the examination of two witnesses.

The OD rejected the opposition. In doing so, it refused to hear the witnesses, reasoning that the documentary evidence (D21–D39) was of such low quality that the skilled person could not extract the technical information needed to assess whether certain claim features were disclosed; in the OD’s view, witness testimony could not remedy those deficiencies and, absent written declarations, would introduce “new facts”. (epo.org)

The opponent appealed and argued that the refusal to hear witnesses infringed the right to be heard under Article 113(1) EPC.

Key findings of the decision 

The Board held that a substantial procedural violation had occurred.

First, it found that the OD had confused the submission of facts with the proof of those facts. In the case at hand, the notice of opposition set out the factual allegations regarding which features were disclosed by the alleged prior use, while the witnesses were offered as a means to corroborate and explain the technical details visible in the diagrams (but requiring expert interpretation). On this basis, the witnesses were not offered to introduce new facts, but to confirm facts already alleged.

Secondly, relying on the established jurisprudence (CLBA 11th ed., section III.G.3.1.1), the Board reiterated that if evidence is offered to prove contested facts essential to the settlement of the dispute and is decisive, it must, as a rule, be taken. The Board considered the disputed features to be essential to the novelty assessment and therefore decisive.

Thirdly, the Board criticised the OD for pre-empting the evaluation of evidence: by deciding that witness testimony could not fill perceived documentary gaps, the OD had effectively proceeded on an assumption about what the witnesses would say. The Board considered this speculative approach incompatible with proper evidence taking.

Fourthly, the Board rejected the OD’s “new facts” rationale. It stated that additional clarifications by a witness to close a potential documentary gap cannot be treated per se as new facts before the witness is heard; otherwise, hearing witnesses would become futile.

Finally, the absence of written witness declarations was not a valid reason to refuse examination. The Board emphasised that it is for a party to choose the means of evidence it considers suitable; the OD must decide on the basis of the relevant evidence available rather than “prefer” documentary items and draw conclusions from their absence.

Analysis and implications 

T 1113/24 underlines that, in public prior use cases (where drawings and system diagrams often require contextual explanation), an OD should not dismiss offered witness evidence by characterising the document set as weak and treating testimony as inherently incapable of curing that weakness. Where the factual framework is already pleaded and the witness is offered to corroborate decisive, contested facts, the OD should normally take the evidence before determining what the prior use does or does not disclose.

Conclusion 

The Board set aside the impugned decision and remitted the case to the OD for further prosecution; it did not decide any substantive issues beyond the procedural deficiency. The appeal fee was reimbursed.

Key points 

The opposition is based on an alleged public prior use. The OD rejected the opposition. The opponent appeals. The OD had refused to hear two witnesses (as requested by the opponent) in connection with the public prior use. The opponent had substantiated the public prior use with documents including technical drawings and diagrams.

The OD had reasoned as follows: “The witnesses had been offered to confirm that the filling and cleaning installation according to the prior use “Adelholzener” anticipates all the features of claim 1 of the contested patent. However the documentary evidence supporting the alleged prior use D21 to D39 was of such a low quality that a skilled person would not be able to read any technical information from the diagrams of documents D23, D24, …, and thus would not be able to identify whether some of the claimed features … were disclosed in these documents or not.”

The Board: “The appellant [opponent] convincingly demonstrated that a substantial procedural violation took place in the opposition proceedings for the following reasons.”

“the [opponent] offered witnesses specifically to corroborate and explain the technical details of the circulation paths that were visible in the diagrams (but required expert interpretation). This means that the witnesses have not been offered to introduce new facts into the proceedings, but merely to confirm the facts alleged in the notice of opposition.”

“According to the established jurisprudence (CLBA, III.G.3.1.1), if the evidence offered as proof of contested facts essential to the settlement of the dispute is decisive, the body hearing the case must, as a rule, order that it be taken.”

“The opposition division also incorrectly based its decision on the prior use on an assumption about what the witnesses would say, thereby pre-empting the evidence’s evaluation.”

“Additional clarifications provided by a witness to close a potential gap in the documentary evidence on file cannot be considered per se, even before hearing the witness, as new facts; hearing a witness would otherwise be futile (CLB, point III.G.2.4.1).”

” The absence of written declarations by the offered witnesses is also not a reason to suspect that their testimony would exclusively introduce new facts, and also does not justify the decision of not hearing them.”

“This is because, according to the established jurisprudence it is a party’s choice to present whatever means of evidence it considers to be suitable, and it is an opposition division’s duty to take its decision on the basis of all the relevant evidence available rather than to expect the presentation of more preferred pieces of documentary evidence, and to speculate on the reasons for and draw conclusions from their absence ”

“While it is correct that oral evidence of a witness should only be taken when required to clarify matters decisive for the decision, the opposition division should have heard the witnesses before deciding what the alleged prior use was, and was not, disclosing, as the witnesses were offered to corroborate decisive facts already alleged in the notice of opposition.”

“By refusing to hear the proposed witnesses before deciding on the allegation of prior use, the opposition division has in fact proceeded to assess evidence that had not yet been completely established thereby incurring a substantial procedural violation …”

The impugned decision is set aside and the case is remitted to the OD. The Board does not decide on any other points.

The link to the decision.

Any questions? Please contact Marco Molling (M.Molling@vo.eu) or Peter de Lange (p.delange@vo.eu)