A more nuanced approach to the evidence standard for prior use (T 1311/21)

Background: Evidence standard for prior use

Traditionally, EPO Boards of Appeal have applied different standards of proof depending on whether evidence of alleged prior use was within the power of one party or equally available to both parties. The case at issue concerned European patent EP2950075, owned by Horiba Ltd, relating to an on-road running exhaust gas test apparatus. The patent claimed an apparatus for vehicle exhaust gas testing comprising an information processing unit connected to a display that could acquire and process running data during road tests. The Opponent, Avl List GmbH, challenged the patent’s validity based on several grounds, including prior public use as evidenced by a user manual describing the invention. 

At Opposition, the patent was maintained in amended form, with the Opposition Division (OD) finding that disclosure of the invention prior to the priority date had not been proven. Both parties appealed the OD decision. The question for the Board of Appeal was whether the user manual had been made available to the public before the priority date without an obligation of confidentiality, and how to assess the standard of proof required given that the evidence was neither fully within the opponent’s control nor equally accessible to both parties.

A more nuanced standard to the assessment of evidence for prior use? 

In T 1311/21, the Board of Appeal addressed the longstanding dichotomy between “balance of probabilities” and “beyond reasonable doubt” standards, and questions whether such a dichotomy in fact made sense. The Board of Appeal noted that EPO case law has applied different standards depending on whether evidence lies within the power of one party (requiring proof “beyond reasonable doubt”) or is equally available to both parties (where “balance of probabilities” suffices). However, in this case, the evidence of prior use fell into neither category cleanly. Whilst the manual originated from the Opponent, it had been delivered to a third party (Daimler AG) and the circumstances of its use were not exclusively within either party’s knowledge.

The Board of Appeal observed that a “binary approach to proof standards can turn out to be overly formalistic and simplistic” (headnote 2). Instead, the Board of Appeal emphasised that “what matters is the deciding body’s conviction on the occurrence of an alleged fact, taking into account the particular circumstances of the case and the relevant evidence before it.” (headnote 2, and r. 3.2.1). In support of moving away from an approach based on a rigid dichotomy, the Board of Appeal cited previous decisions T 1138/20 and T 1634/17. T 1138/20, for example, found that making a distinction between the above-mentioned standards is neither necessary nor mandated by case law. Similarly, in T 1634/17, it was found that there was no need to take a stand on the question which standard of proof to apply.

In the present case, the Board of Appeal was of the view that applying a more flexible approach to the assessment of evidence would align with the complex reality of many prior use cases, where evidence may be partially available to both parties, or may lie primarily with third parties. Rather than trying to force such situations into one of two categories, the Board of Appeal advocated for a holistic assessment of the evidence in its context. 

Importantly, however, the Board of Appeal also emphasised that the more flexible approach to assessing the evidence for prior use it proposed would not mean a lowering of the bar for proving prior use. On the contrary, the Board of Appeal argued, it would mean a greater focus on whether the totality of evidence, considered in its proper context, was convincing of an alleged prior use. Such an approach might include consideration of factors such as the nature of the alleged use, the commercial context, the reliability of the evidence, and any circumstances that might affect its availability to the parties.

Reliance on general terms of confidentiality 

Having decided on what approach it should take, the Board of Appeal reviewed the chain of evidence regarding the public availability of the a user manual for the AVL MOVE System Control software. The OD had found the user manual not to be prior art, and so had not fully considered the novelty and inventive step of the claim invention in view of the manual. Key evidence cited by the Opponent that the manual should be considered prior art included delivery notes showing the shipment of the user manual to another company, Daimler AG. The Board of Appeal was convinced by this evidence that the relevant version of the manual was delivered to Daimler AG before the patent’s priority date. 

The question then became whether conditions of confidentiality could be said to have applied to the manual. The Board rejected arguments from the patentee that the confidentiality of the manual was implied. Particularly, the Board of Appeal noted that user manuals for commercially available products are typically not subject to confidentiality obligations. 

The patentee also referenced the mention of AVL’s General Terms and Conditions in the delivery note and also noted standard industry practice. However, the Board of Appeal was not convinced by these arguments. First, the Board emphasised the commercial reality that the AVL MOVE system described in user manual was not a product produced for a single customer, but for many, with the manual intended for delivery to all purchasers. The Board noted that imposing confidentiality obligations on such widely distributed user manuals would be impractical and nearly impossible to enforce. The Board emphasised that user manuals, by their nature, merely describe how to use an already purchased product and thus wouldn’t typically be subject to confidentiality restrictions. Additionally, the cited purchase documentation revealed that Daimler AG’s own purchasing conditions were applicable to the case, potentially neutralising any effect of AVL’s standard terms. 

The Board of Appeal concluded that the user manual was prior art and remitted the case back to the Opposition Division for an assessment of novelty and inventive step.

Final Thoughts

The issue of prior use is, of course, a hot topic at the moment as we await the outcome of the referral to the EBA in G1/23 (IPKat). The issue also came up in the recent decision concerning the morality of inventions derived from indigenous people by immoral means (IPKat). As the Board of Appeal notes in the present case, both demonstrating or defending against an allegation of prior use can be challenging, as the form of evidence is often less than perfect (IPKat). 

The Board of Appeal’s approach in this case suggests that future cases involving prior use should focus less on arguing about which standard of proof applies, and more on presenting comprehensive evidence that allows the deciding body to form a clear conviction about what occurred.

Further Reading

• The free evaluation of evidence of prior use (T 0042/19) (May 2023)
• New EBA referral: When is prior use of a product excluded from the prior art for lack of enablement? (June 2023)
• The morality (and patentability) of inventions derived by immoral means (T 2510/18) (Oct 2024)