5.1.2 Individual cases
This section reports on several cases. Issues of proof in relation to Art. 56 EPC are inextricably linked to the assessment of inventive step discussed in chapter I.D "Inventive step".
In T 547/88 inventive step had been contested. Although the board had asked the parties to issue a joint protocol stating what tests had to be done and under what conditions, each party had in fact conducted its own experiments and obtained contradictory results. It was therefore not possible for the board, on the basis of these tests, to conclude definitively that no inventive step was involved. The board held that in such a case the patent proprietor should be given the benefit of the doubt with regard to the relevance of the claimed features to the problem to be solved. Moreover, since the prior art did not suggest the subject-matter of the contested claims, that subject-matter implied an inventive step. The patent was therefore maintained.
The burden of proving that the claimed method leads to the advantageous effects mentioned in the patent in suit rests with the patentee. In the absence of any corroborating evidence that these advantageous effects were obtained, the alleged effects are not to be taken into account when assessing inventive step (cf. T 97/00; see also T 1409/04).
In T 862/11 the appellant (opponent) had failed to submit comparative tests in support of its own assertion that an improvement was implausible owing to the lack of any evidence. In the absence of such tests, however, it failed to convince the board, which therefore regarded the problem as solved, and saw no need to reformulate it.
The problem stated in a granted patent is deemed to have been plausibly solved by the claimed invention when there are no grounds to suspect otherwise. According to the established case law of the boards of appeal, in opposition (or any subsequent appeal) proceedings, it is insufficient for the opponent to attack a granted patent with an unsubstantiated assertion. The opponent bears the burden of proving its assertion or must at least furnish evidence liable to raise doubts that the problem has indeed been solved (T 534/13, citing T 1797/09, point 2.7 of the Reasons). If the opponent succeeds in doing so, the burden shifts to the patent proprietor to prove its assertions (see e.g. T 1797/09).
The board in T 291/15 observed that, according to established case law, each party bears the burden of proof for the fact it alleges. This means that a technical problem set out in a patent is considered to be credibly solved by a claimed invention if there are no reasons to assume the contrary. In such circumstances, the onus is normally on the opponent to prove the opposite by appropriate counter-evidence or to at least provide evidence casting doubt on the alleged solution of the problem (T 596/99, point 7.2.9 of the Reasons and T 1797/09, point 2.7 of the Reasons).
In T 2320/16 the opponent (appellant) alleged, with reference to T 415/11, that the burden of proof in relation to the problem-solution approach lay with the respondent (patent proprietor). The board disagreed, holding that it was insufficient in opposition proceedings for the opponent to challenge a granted patent with an assertion which had not been substantiated. The appellant (opponent) had not submitted any evidence which cast doubt on the claimed effects.
In T 1177/17 the question arose as to whether 2-FL could, by itself, provide the claimed indirect antiviral effects by means of NK cell stimulation, as alleged by the respondent (patentee). In the board's view, it could not. There was no evidence on file to show this, the respondent not having substantiated its submissions with any evidence other than the data reported in example 1 of the patent – a study in mice vaccinated with Influvac. On the contrary, it had argued that it was down to the appellants (opponents) to demonstrate that 2-FL did not provide the claimed antiviral effects by means of NK cell stimulation. However, in the board's view, this argument could not succeed since the technical effects invoked by the respondent were not plausible over the whole scope of claim 1 of the main request.
In case T 655/13 the examining division did not precisely identify the passage of document D1 (technical journal in Japanese as a prior art publication) which disclosed the feature in dispute and at the same time did not provide a translation of at least the referenced longer section of said Japanese document. The board recalled that in examination proceedings, as far as issues relating to patentability requirements are concerned, the burden of proof – and consequently the onus of presentation of the relevant facts – lies initially with the examining division, which must provide evidence and facts to support its objection (see T 578/06). As a rule, the applicant can dispute in a general way a general statement made by the examining division, which then in turn is obliged to raise a more detailed objection. In order to give an applicant a fair chance to challenge the findings of the examining division, the latter should, as a rule, at least once identify where in the closest prior art document each of the features of the claim in suit is disclosed (see e.g. the obiter dictum in T 70/02).
The board in T 1285/21 dealt with the question of the burden of proof with regard to proving a technical effect, in relation to the issue of experimental data and remaining doubt. In the specific case of establishing that the claimed invention is associated with a technical effect, it is incumbent on the patent proprietor to prove that the claimed subject-matter leads to the advantageous effects mentioned in the patent in suit. Moreover, the board did not see any reason to relax this rule in the opposition phase (as opposed to during the examination phase), not even in cases where the contested patent disclosed comparative examples related to the distinguishing features. It was noted in particular that new prior art documents can be submitted in the opposition proceedings, potentially resulting in a complete reassessment of novelty and inventive step. In those cases, the opposition division and board may have to analyse the examples of the contested patent again and examine whether they make it credible that a technical effect is achieved over the closest prior art. The burden of proof shifts only when a technical effect has been plausibly demonstrated, it then being incumbent on the opponent to furnish evidence in support of its counterarguments. According to decision T 1797/09, a technical problem set out in a patent is credibly solved if there are no reasons to assume the contrary. By implication, though, this would mean that it would first be down to an opposing party to substantiate why the problem addressed is not solved (negative evidence), rather than it being incumbent on the patent proprietor to present grounds or evidence (positive evidence) in support of a technical effect. This decision therefore appears to suggest that the burden of proof is initially with the opponent. However, the board in T 1285/21 also underlined that T 1797/09 still works on the assumption that even if a technical effect is presumed, this can be rebutted in opposition or appeal proceedings. Accordingly, the board in T 1797/09 denied the technical effect – which had merely been alleged – in view of the evidence submitted by the opponent.
- T 0449/23
In T 449/23, regarding claim 1 of auxiliary request 1 (claims 1 and 2 being identical to claims 2 and 3 of the main request, after claim 1 of the main request was deleted following a finding of lack of inventive step over D5), the board came to the conclusion that the alleged effects of the distinguishing features were not credible, contrary to the arguments of the patent proprietor. Hence, any alleged effects arising from this comparison could not be taken into account in the formulation of the objective technical problem. The patent proprietor also argued that the burden of proof lay with the opponent to demonstrate that the alleged technical effects were not present. The board disagreed, stating:
(a) that the legal burden of proof was the duty of a party to persuade the deciding body of allegations of facts on which the party’s case rested. In principle, a party must prove alleged facts (assertions) from which it infers a legal consequence, i.e. which establish the basis for the party's legal claims. Thus, the allocation of the burden of proof depends on a party’s substantive case.
(b) that to discharge its legal duty of persuasion, a party must prove the alleged facts by appropriate evidence to the required standard of proof. The party with whom the legal burden of proof lies therefore bears the risk that the alleged facts remain unproven, and thus that the deciding body will decide against that party and reject its legal claims. Thus, the legal burden of proof requires the production of appropriate evidence to persuade the deciding body to the required standard.
(c) that in principle the legal burden of proof does not shift. References in the case law to a shift of burden of proof relate to the so-called evidentiary/evidential burden of proof (see for this distinction T 741/91), the notion of which relates to the state of the evidence produced in the course of proceedings. Once the party bearing the legal burden of proof has adduced sufficient evidence to support its allegations of facts to the required standard of proof, the onus is on the adverse party to rebut the asserted facts with appropriate evidence. Otherwise, the adverse party risks that the deciding body is persuaded of the existence of the facts and allows the claims. Thus, if the party having the legal burden of proof has made a "strong case" by filing convincing evidence, the onus of producing counter-evidence shifts to the adverse party. However, this does not mean that the legal burden of proof is on the adverse party to prove the non-existence or the contrary of asserted factual allegations. It is sufficient that the adverse party raises substantiated doubts that prevent the deciding body from being persuaded of the existence of the alleged facts.
(d) that in opposition and opposition-appeal proceedings, each of the parties carries the legal burden of proof for the asserted allegations of facts on which their respective substantive case rests. As regards an alleged lack of inventive step, the burden is on the opponent to adduce appropriate prior art which – when following the established substantive test, i.e. the problem-solution approach – persuades the opposition division or the board of the obviousness of the solution provided by the subject-matter claimed. On the other hand, if the patent proprietor asserts that, in comparison to the prior art, there is an advantage or effect giving rise to a more ambitious formulation of the objective technical problem than that presented by the opponent and hence to an inventive step, the burden of proving this advantage or effect to the required standard of proof is on the patent proprietor. The mere assertion in the patent specification of an advantage or effect cannot be regarded as evidence of such an assertion.
The board listed a number of decisions (T 97/00, T 355/97, T 1097/09, T 1392/04), in which the underlying circumstances were comparable, confirming these principles. The board also observed that T 1797/09 submitted by the patent proprietor remained a singular decision not followed. The subject-matter of claim 1 of auxiliary request 1 lacked inventive step.