4.3. Standard of proof
Overview
4.3. Standard of proof
Even though different concepts as to the standard of proof have developed in the case law of the boards, they all have in common that a judgement is to be made on the basis of the application of the principle of free evaluation of evidence (confirmed by G 2/21, point 46 of the Reasons).
The board in T 1138/20, a case that turned on issues of proof, clearly stated (see point 1 of the Catchword) that there is only one standard of proof in the proceedings before the EPO: the deciding body, taking into account the circumstances of the case and the relevant evidence before it, must be convinced that the alleged fact has occurred. (See also T 1138/20 point 1.2.3 of the Reasons, on the obligation to give reasons).
Compare G 2/21 (OJ 2023, A85), which contains the following passage: "The only decisive factor is whether the judge is personally convinced of the truth of the factual allegation, i.e. how credible the judge classifies a piece of evidence. To do this, the judge must put all the arguments for and against a factual statement in relation to the required standard of proof. (…) The reasons that led the judge to be convinced of the correctness or incorrectness of a contested allegation as to fact are to be set out in the decision." (see point 31 of the Reasons, and also point 46 of the Reasons cited above). T 832/22 analyses decisions including G 1/12, G 2/21 (points 30-31 of the Reasons) and T 1138/20 with regard to the relationship between the principle of free and unfettered consideration of evidence, conviction of the deciding body and standard of proof.
When a standard is applied, the EPO standard of proof is generally the balance of probabilities. By way of exception, the standard of proof of the balance of probabilities is shifted to a standard of proof beyond reasonable doubt mainly in opposition where only the opponent has access to information (evidence) concerning, for example, an alleged public prior use.
The board in T 1138/20 stated that if, for example, only the opponent had access to the relevant evidence, this fact must be given due consideration in the deciding body's assessment as to what weight and importance are to be attached to such evidence. This was not the same as to say that a different standard of proof should apply.
In T 778/21 the board firstly noted that the prior use occurred within the knowledge and control of the opponent and concerned the use of a specific machine. Even if the machine type was publicly available for sale, the alleged instance of prior use concerned the one specific machine to which the proprietor had no access. In such cases, the board stated that it is established case law that the required standard of proof was either “beyond all reasonable doubt” (T 97/94) or that the deciding body had to be convinced with a sufficient degree of certainty (T 1138/20, T 545/08).
Of note are some other, earlier decisions containing lengthy observations on the standard of proof and the previous case law on this, namely: T 2451/13 on the meaning of "beyond reasonable doubt" and T 545/08 on the meaning of "balance of probabilities" in the boards' case law; in the latter decision, the board considered the matter in the general context of the law of evidence, concluding that a probability as low as 51% would not suffice.
T 1138/20 contains very detailed reasoning on the standard of proof applicable before the EPO, identifying decisions (T 545/08, T 768/20, T 660/16, T 1634/17) where it was not deemed necessary to explicitly decide on the applicable standard and it was instead emphasised that what mattered was whether the board was convinced. And the board in T 1138/20 considered that making a distinction between the above-mentioned standards was neither necessary nor mandated by case law.
Indeed, several decisions have not considered it necessary to decide explicitly which standard of proof applied: see T 2466/13, in which it was found that there was no need to decide on the applicable standard of proof. In the same vein, see T 768/20, T 660/16 citing in particular T 545/08 (points 8 and 11 of the Reasons). In T 464/20, the appellant challenged the standard of proof (balance of probabilities) used at first instance to conclude that prior use had been proven. However, the board held that the opposition division had linked its application of the standard to whether it was persuaded that the alleged facts were true. The board was thus not convinced that it had been wrong to apply the standard of the balance of probabilities, especially as the opposition division had been persuaded of the truth of the alleged facts (T 768/20 being concurred with). T 34/08 was another case where the board concluded that it was convinced without referring to a standard of proof. T 1634/17 (point 19 of the Reasons) stated that there was no need to take a stand; what was decisive was that, in view of the evidence before the first-instance department or the board in an individual case, the deciding body was persuaded that a particular oral disclosure had taken place and particular information had been conveyed to the audience or not.
The board in T 1311/21 agreed with T 1634/17 and T 1138/20, and decided that the two standards of proof in the jurisprudence of the boards of appeal – "balance of probabilities” and “beyond reasonable doubt” – may well be used as a yardstick in straightforward cases. However, this binary approach to standards of proof could turn out to be overly formalistic and simplistic. If evidence whose public availability prior to the priority date of the patent was at issue was neither within the sphere of control of the opponent nor within a neutral sphere of control to which both parties had access, neither standard of proof was exclusively applicable; rather, what mattered was the deciding body's conviction of the occurrence of an alleged fact, taking into account the particular circumstances of the case and the relevant evidence before it.
The board in T 832/22, with reference to the case law and the principle of free evaluation of evidence (G 1/12, G 2/21 points 30-31 of the Reasons), stressed that the standard of proof referred to the nature or degree of personal conviction that the members of the deciding body had to have in order to be satisfied that an alleged fact had occurred. If the applicable standard of proof was that which has been termed "the balance of probabilities", an alleged fact was proven as soon as the members of the deciding body were convinced that the occurrence of that fact was more likely than not. If the applicable standard of proof was that which has been termed "beyond reasonable doubt", the required degree of personal conviction of the members of the deciding body was higher. The board explained that it was difficult to quantify the difference in the required degree of conviction between the "balance of probabilities" and "beyond reasonable doubt" standards. In fact, attempting to describe this difference in the form of numerical thresholds, for example as a certain percentage of likelihood that an alleged fact occurred, could even be misleading. The "beyond reasonable doubt" standard did not require absolute certainty, and it was sufficient if the (majority of the) members of the deciding body had no reasonable doubt than an alleged fact had occurred. In other words, even if there was some remaining doubt, the "beyond reasonable doubt" standard of proof could be met as long as the remaining doubt was not reasonable. In any case, the board stated that if the higher of two disputed standards of proof has been met, it could be left open which of these standards must be applied when assessing the evidence in question. Hence, if the deciding body is convinced beyond a reasonable doubt that an alleged fact occurred, there is no need to decide which standard of proof is applicable.
In T 1808/21, on the question of whether appellant 1 had circumvented the law by allegedly lowering the standard of proof required for the public availability of D5 due to its role as a "straw man", the board was convinced that a distinction between the "balance of probabilities" standard and the "beyond any reasonable doubt" standard was not decisive in that case. In line with T 768/20 and T 660/16, the board agreed that the relevant point was instead whether the deciding body was ultimately persuaded in view of all the available facts that the relevant evidence, which had been duly presented by appellant 1 when it filed its opposition, had indeed been made publicly available.
- T 0733/23
In T 733/23 the opposition division had concluded that there had been insufficient evidence to prove that the data sheets D2, D4, and D7 to D9 had been made available to the public before the filing date. Rather than concluding that, as a result of the data sheets not being considered state of the art under Art. 54 EPC, the subject-matter of the claims was novel, the opposition division decided not to admit them into the opposition proceedings. The board concluded that not admitting these data sheets, filed in due time, constituted a substantial procedural violation (see details as from point 4 of the Reasons including discussion on D19, an affidavit).
The board, in support of its decision, presented some key considerations on public availability of advertising brochures and data sheets, as well as the standard of proof to be applied. The board stated that when a document was clearly intended to be publicly distributed, as was the case with advertising or commercial brochures, the absence of a specific publication or distribution date, a situation quite common in this type of document, was not in itself sufficient to conclude that the document did not constitute prior art. As with any other type of evidence, the key question was not whether the exact date of publication could be determined, but whether it could be established that the relevant subject-matter was made available to the public before the priority or filing date.
Data sheets often represent an intermediate case between internal documents and advertising brochures. Where no publication date is present, the board held it should first be assessed whether the document was intended for public distribution. If so, additional sources must be examined to establish whether the relevant subject-matter was publicly accessible before the patent’s filing or priority date. Here, the opposition division had failed to provide a reasoned decision on public availability, giving no weight to the dates printed on their front pages.
As to the standard of proof, the present board concurred with the position in T 1138/20 that there is only one standard of proof: the deciding body must be convinced, based on the underlying circumstances.
According to the present board, this did not imply that all cases were to be treated identically, as in practice the degree of proof required to establish credibility (i.e. to persuade the board) might vary depending on the specific circumstances. In other words, it was not the standard of proof that adjusted with the circumstances, but rather the credibility of the arguments made by the different parties. For example, when the evidence was exclusively controlled by one party, any gaps in the relevant information might significantly undermine that party's credibility. Conversely, when the information was equally accessible to both parties but only one party submitted evidence, merely raising doubts might not be sufficient to challenge the credibility.
In the present case, the conclusions of the opposition division suggested that the standard of proof "up-to-the-hilt" was applied to determine the public availability of the data sheets. Even if the board agreed that different standards should be applied, this would not be justified in the case in hand, as the relevant information to prove the public availability of the data sheets was not within the exclusive sphere of the appellant (opponent). In this instance, the relevant information would more likely be within the sphere of the patentee. Therefore, there was no basis for applying the strict standard of "up-to-the-hilt" or for questioning the credibility of the appellant (opponent) solely on the grounds that some information was missing.
The patentee argued that, when in doubt, the patent should be upheld. The board disagreed. Fact-finding boiled down to a binary exercise: either something had been proven, or it had not. In addition, there was no presumption of patent validity in proceedings meant to re-assess the validity of this very patent.
- T 2463/22
In T 2463/22 the opposition division had held that the prior uses had not been proven beyond reasonable doubt (up to the hilt), in particular with regard to whether the products of the prior uses had actually been delivered. The parties before the board focused on which standard of proof had to be applied in view of G 2/21 and T 1138/20 and whether the applicable standard had been met. In the respondent-proprietor’s view, T 1138/20 was an isolated decision, not compatible with G 2/21.
On the required standard of proof, the present board observed that G 2/21 recognised that different concepts as to the standard of proof had been developed in the case law. According to T 1138/20 only one standard should be applied, namely "the deciding body must be convinced, taking into account the circumstances of the case and the relevant evidence before it, that the alleged fact occurred".
In the present board's view, under the principle of free evaluation of evidence, it was always decisive in the evaluation of evidence that the members of the deciding body were personally "convinced". Moreover, they had to always be convinced of whether, as stated in T 1138/20, "the alleged fact has occurred". The board stated this was true regardless of which standard of proof was applied. The standard of proof refers to the nature or degree of conviction that the members of the deciding body must have to be satisfied that an alleged fact occurred (see T 832/22).
According to the board, and with reference to a UK House of Lords decision, two important aspects had to be stressed. Firstly, that the standard of proof is related to the required degree of conviction of the members of the deciding body. Secondly, that it is not related to what is evaluated by the deciding body. Hence, also when a lower standard of proof such as the balance of probabilities is applied, the deciding body must assess whether or not the alleged fact indeed occurred. In other words, also when such a standard of proof is applied, the question is not whether the alleged fact might have occurred with some probability. The board considered G 2/21 (points 31 and 45 of the Reasons) consistent with this understanding.
The more specific question as to whether there was only a single standard of proof or more than one could be left unanswered according to the board. The board held that if the deciding body was convinced beyond reasonable doubt that an alleged fact had occurred, there was no need to decide how many standards of proof there were and which one was applicable (see T 832/22).
The board then gave some consideration to the assessment of factual allegations using the beyond reasonable doubt standard of proof. The European Patent Organisation being an independent international organisation, the board stated the standard had an autonomous meaning within this autonomous legal order. Secondly the board agreed with T 832/22 that it seemed expedient to focus on the term "reasonable".
The board then considered the prior uses, focusing especially on prior use relating to the sale of product 5 (sample of a powder mix from a specific lot number), the content of the sample and whether it was available to the public. In view of all the information (including invoices, affidavit, emails, test report, excerpt from database), which also involved evidence provided by a third party (the buyer), the board was convinced beyond reasonable doubt that product 5, with a specific lot number, was sold prior to the effective date of the patent. Since it had also been shown that product 5 disclosed all features of claim 1, lack of novelty prejudiced the maintenance of the patent as granted. Concerning the third auxiliary request, product 5 was suitable for use as closest prior art. The board referred to the reluctance sometimes in the case law to treat an object of a prior use as the closest prior art. Often, there was neither information on what the object did and what properties it had in the technical environment in which it was applied nor on how the process for its manufacture could be modified. These considerations indeed spoke against regarding a prior use as a suitable starting point for assessing inventive step. In the case in hand however, the skilled person was faced with a different situation. The board concluded that the third auxiliary request did not involve an inventive step. The decision of the opposition division was set aside and the patent revoked.