"Burden of proof" refers to the obligation placed on a party to legal proceedings to support their assertions. The proof submitted by a party to successfully substantiate their assertions is required to meet a certain "standard of proof" – the degree to which a party must prove its case.
Burden of Proof
At the European Patent Office (EPO), the burden of proof typically starts with the examiner who first raises objections against an application. If the examiner's arguments meet the standard of proof required, the burden of proof subsequently shifts to the applicant who must prove why the examiner's objections are unconvincing.
In opposition proceedings, the burden of proof initially lies with the opponent. For example, if an opponent asserts that a patent should be revoked on grounds of the granted claims lacking novelty, it is up to the opponent to provide evidence that the subject matter of the granted claims was indeed available to the public prior to the effective filing date.
A case (T 1076/21) recently brought before the EPO Board of Appeal addressed the question of whether the burden of proof automatically shifts to a patent proprietor whose patent has been revoked by an opposition division due to insufficiency.
The Board's preliminary opinion had disagreed with that of the opposition division; the patent probably did satisfy the requirements of sufficiency of disclosure.
The respondent (opponent) then filed a letter in response to this preliminary opinion. In this letter, the respondent again argued the alleged lack of sufficiency in the patent. Further, the respondent assumed the preliminary opinion's disagreement with the opposition division meant the burden of proof had shifted back to them, thus the Board ought to give them the opportunity to refine their arguments using a joint expert declaration, annexed to their letter.
The Board confirmed that the burden of proof does not shift to the patent proprietor just because the patent had been revoked. Whether or not the burden of proof can shift depends entirely on the existence of serious doubts which are backed-up by verifiable facts. Due to the respondent's failure to submit evidence to substantiate their claims during opposition proceedings, the Board confirmed that the burden of proof still lay with the respondent. The respondent's joint expert declaration was not admitted into the proceedings as it was considered to have been filed too late, and thus their assertions of a lack of sufficiency in the patent remained unsubstantiated. The Board concluded that the opposition division's decision to revoke the patent was erroneous.
The outcome of T 1076/21 emphasizes the importance of having evidence to substantiate your claims as an opponent during opposition proceedings, particularly when asserting on the notoriously difficult grounds of insufficiency.
Standard of Proof
The EPO generally holds the standard of proof of the "balance of probabilities", meaning evidence needs to be persuasive enough to make arguments seem "more likely true than not". The standard of proof of the balance of probabilities sometimes shifts to the stricter standard of proof of "beyond reasonable doubt"; this can occur in cases such as opposition proceedings where only the opponent has access to certain information that can be used as evidence against the patent proprietor.
In a recent case (T 1138/20) before the EPO Board of Appeal, questions were raised as to whether evidence submitted by a respondent during opposition proceedings had met the standard of proof required, and what exactly that standard of proof was.
T 1138/20 follows an interlocutory decision made by the opposition division to allow a patent to be maintained in accordance with a second auxiliary request made during opposition proceedings, the auxiliary request a consequence of novelty-destroying evidence submitted by the opponent. The patent proprietor appealed this decision, arguing that non-patent literature 1 (NPL-1) submitted as evidence by the opponents had not been proven beyond reasonable doubt, the expected standard of proof according to the opposition division. The opposition division had found that NPL-1 was a presentation delivered to the opponents and then published on their website, therefore available to the public before the effective filing date of the patent. The reason given for applying this higher standard of proof was that the patent proprietor was not involved in the alleged events surrounding NPL-1, and therefore could not disprove the allegations.
The Board, looking at prior cases, noted that either of the two standards of proof could be applied when concerning the issue of prior art being available to the public before an effective filing date of a patent, depending on the circumstances of the case. The standard of beyond reasonable doubt had been applied in cases where most, if not all, evidence lies "within the sphere of the opponent".
The Board, having reviewed prior cases, concluded that the circumstances of the case, such as all evidence lying within the sphere of the opponent, must be given due consideration in the deciding body's assessment as to the weight and importance applied such evidence. However, the Board stated that this is not the same as saying that a different standard of proof should apply. Rather, a board may be more easily convinced by evidence that is allegedly publicly available than by evidence only available to the party to whom such evidence benefits.
The Board considered that distinguishing between the two standards of proof is "neither necessary nor mandated by case law". Instead, 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." In view of the facts before them, the Board dismissed the appeal, deciding that this single standard of proof had already been achieved by the opponents in the opposition proceedings. Following this decision, patent proprietors and opponents alike should be conscious of the EPO assuming this stance of "only one standard of proof" during proceedings.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.