The Burden of Proof in Petitions for Review: R 0023/24 on Negative Facts
The Enlarged Board of Appeal clarifies the burden of proof for procedural violations during oral proceedings. R 0023/24 departs from earlier case law, ruling that parties bear the burden of proving negative facts about hearings.
Picture defending a European patent in oral proceedings where the debate shifts to a witness testimony from the opposition proceedings, only to find later that the minutes omit this discussion entirely. When the written decision subsequently revokes the patent based heavily on that exact testimony, the immediate procedural reflex is to allege a violation of the right to be heard. But how does a party prove that a document was never discussed? In R 0023/24, the Enlarged Board of Appeal addressed exactly this tension, clarifying the burden of proof for procedural events and expressly departing from earlier case law on negative facts.
How did the dispute over document DF reach the Enlarged Board of Appeal?
The petition for review arose from decision T 0575/23, which revoked a patent for a high-safety ironing board based on prior public use. The Technical Board of Appeal concluded that the claimed child safety lock was disclosed in the prior art, relying on the written testimony of a witness, Mr. Fischer (document DF). The patent proprietor filed a petition for review under Article 112a(2)(c) EPC, alleging a fundamental violation of the right to be heard. The proprietor asserted that document DF was never discussed during the oral proceedings. To support this, they pointed out that the document was absent from the written appeal submissions, the Board's preliminary opinion, and the minutes of the oral proceedings.
Who bears the burden of proving a negative fact about oral proceedings?
The core legal question was whether the patent proprietor had to prove that the discussion did not take place. The proprietor argued that proving a negative fact is inherently impossible, invoking the principle "negativa non sunt probanda" and relying on previous Enlarged Board of Appeal decision R 15/11.
The Enlarged Board of Appeal rejected this argument for events occurring during oral proceedings. The Enlarged Board reasoned that a shift in the burden of proof is only justified when there is a significant gap between the parties in their ability to provide evidence. For oral proceedings, no such gap exists: both sides participate and have equal access to the same types of evidence, such as personal recollections and handwritten notes. Consequently, the Enlarged Board held that the general rule applies. The party alleging a procedural defect must prove the facts supporting its allegation (reasons 2.2.2.3). In doing so, the Enlarged Board explicitly stated it did not share the contrary view expressed in point 5 of R 15/11.
How did the Enlarged Board evaluate the conflicting evidence?
With the burden resting on the patent proprietor, the Enlarged Board applied the principle of free evaluation of evidence to the competing accounts. The proprietor submitted a sworn statement from their representative, attesting under French penal law that document DF was never mentioned.
The opponent and the intervener countered with detailed written and oral statements confirming that the document was discussed extensively. The intervener's representative even provided handwritten notes taken during the hearing, which explicitly linked the rack feature to the child safety lock on a specific page of the testimony. The Enlarged Board weighed the sworn statement against the consistent accounts and contemporaneous notes of the opposing parties. It concluded that the proprietor failed to establish, on the balance of probabilities, that the document was ignored (reasons 2.4.3).
What should practitioners change when documenting oral proceedings after R 0023/24?
This decision limits the application of the principle "negativa non sunt probanda" for procedural omissions. The mere absence of a topic in the minutes is insufficient to prove it was not discussed. The Enlarged Board emphasised that if a party believes the minutes are incomplete, they should actively request a correction to obtain a formal position from the Board.
Furthermore, the reliance on handwritten notes by the intervener highlights a critical practice point. Representatives should maintain meticulous, contemporaneous records during oral proceedings. If a decisive document is introduced unexpectedly, the representative should ensure their objection is explicitly recorded. Waiting for the written decision and attempting to prove a negative in a petition for review is a strategy that is unlikely to succeed for events occurring during oral proceedings.
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Further Reading
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