T 1911/17 - Burden of proof technical effect

Key points

•  In this opposition appeal, "the opponent submitted that, in view of the proprietors' position that antibody 20G7 [specified in the claim] performed better than antibody 24C5 [used in the closest prior art], the burden to proof this was with the proprietors" 
• The Board: "The "legal burden of proof" is on the party who relies on a legal consequence arising from an alleged positive fact. Accordingly, the "legal burden of proof" is determined by the legal cases which each party presents. The "legal burden of proof" (unlike the "evidential burden of proof") does not shift (see decision T 301/95, OJ 1997, 519, point 6.2.3 of the Reasons). " 
• The terms legal burden of proof and evidential burden of proof don't ring a bell with me.
• The explanation in T301/95: " 6.2.3 Under English law, a distinction is drawn between "legal" or "persuasive burden of proof" and "evidential burden of proof". The former rule usually places the burden of proof on the party making an allegation. This apportionment of the burden of proof usually remains the same throughout the proceedings. In the case of "evidential burden of proof", the apportionment may change continually in the course of the proceedings and be transferred from one party to another." 
• T301/95 in fact undertakes a review of the law of evidence in Germany, England and France and is quite interesting, also on that it concludes that none of the national laws can be applied in proceedings before the EPO for the matter of straw man opponents (which were then not yet permitted).
• However, even after reading T31/95 and the present decision, I don't understand what the relevance of the evidential burden is. In particular, the present Board says that " If the party bearing the "legal burden of proof" fails to demonstrate to the required degree the fact(s) on which its legal case rests, the board has to decide against that party."
• From some USA websites, I understand the term 'evidential burden' is used by common law lawyers to identify the level of proof that is initially required in order to get permission to present a contested fact to the jury in a jury trial (for what could be the original source of the term "evidential burden", actually in UK law, see N. Bridge, Modern Law Review 12(3) p.273-289 (1949) full pdf here, paragraph bridging p.276-277: " This burden sets up before the party who bears it a preliminary legal hurdle which must be surmounted before the jury shall be entitled to consider the question of fact in issue. This burden I propose to call the evidential burden of proof.")
• " There is no shift of the legal burden of proof in the appeal proceedings. Although an appellant must argue on appeal why the contested decision was wrong, this does not result in a shift of the legal burden of proof on the substance (see decisions T 1210/05, point 2.3 of the Reasons and T 1608/13, point 3.1 of the Reasons)." 
• T210/05: " Before the opposition division it is the opponent who bears the burden of proof as regards demonstrating that the patent does not fulfil the requirements of the EPC. Appeal proceedings do not result in a shift in the burden of proof in the way suggested by the respondent [opponent] - that is towards a requirement that the appellant prove a negative [namely, that a certain poster was not presented]. It is clear that in the case where the opposition division has revoked a patent, the appellant must argue before the board why this decision was wrong" 
• T 1608/13 r.3.1: " Referring to T 585/92 the respondent argued that in appeal, after the Opposition Division had revoked the patent [for insufficiency of disclosure based on an ill-defined parameter], the burden of proof was shifted to the appellant to prove that the decision was wrong. However, the primary aim of appeal proceedings is to review the decision under appeal on the basis of the submissions and requests of the parties. This clearly encompasses the review of the Opposition Division's reasoning, in particular the assessment of the respondent's objections considered in the decision. If the reasoning as such is found to be wrong, there cannot be any shift of the burden of proof on the substance. As regards the latter, it is established jurisprudence that a successful objection of lack of sufficiency presupposes that there are serious doubts substantiated by verifiable facts []. It is primarily the respondent's duty to provide such facts in support of its objections." 
• Turning to the technical effect: " The legal burden of proof lies with the opponent to establish that the claimed invention lacks an inventive step. The opponent must therefore set forth the state of the art which makes the claimed invention obvious to the person skilled in the art. If, in support of an inventive step, a patent proprietor alleges that the claimed invention has advantageous properties or effects, then the legal burden of proof for the alleged improvement over the prior art rests upon them (see decision T 97/00, point 3.1.6 of the Reasons)." 
• T97/00:  The patentee/respondent asserts that " the problem to be solved consisted in providing a process for activating a catalyst having an increased activity, an improved stability and a higher selectivity to C5+ hydrocarbons, as described in the patent in suit, column 2, lines 23 to 31" ... "  in the present case, the burden of proof for showing that the claimed method leads to the alleged and not supported advantageous effects mentioned in the patent in suit, rests upon the Respondent-Patentee. In the absence of any corroborating evidence that said advantageous effects are obtained, the allegation in the patent in suit of increased activity, improved stability and higher selectivity are unsubstantiated and, consequently, such alleged effects are not to be taken into account in assessing inventive step."
• Which leads us straight to G2/21 Plausibility
• After analysing the facts at hand:  "On the basis of the evidence on file, the board cannot conclude that antibody 20G7 is generally superior to antibody 24C5 in detecting BNP(1-32) and proBNP(1-108)." 
• Follows the entire reasoning on obviousness: " In the board's view, a person skilled in the art starting from the closest prior-art antibody 24C5 would have been able to provide alternative antibodies capable of binding to BNP(1-32) and proBNP(1-108) using routine methods. Under the case law of the boards of appeal in these circumstances, the claimed subject-matter, i.e. antibodies, is obvious (see e.g. decisions T 735/00, point 26 of the Reasons; T 187/04, point 11 of the Reasons; T 511/14, points 3 and 5 of the Reasons; T 605/14, points 23, 24 and 26 of the Reasons). Therefore, the subject-matter of claim 2 does not involve an inventive step (Article 56 EPC)." 

EPO 

The link to the decision is provided after the jump, as well as (an extract of) the text of the decision.

https://www.epo.org/law-practice/case-law-appeals/recent/t171911eu1.html

22. Consequently, the difference between the closest prior-art antibody 24C5 and the antibody 20G7 referred to in the claim is their structure.

Technical effect of the difference

23. The opponent submitted that, in view of the proprietors' position that antibody 20G7 performed better than antibody 24C5, the burden to proof this was with the proprietors.

24. The "legal burden of proof" is on the party who relies on a legal consequence arising from an alleged positive fact. Accordingly, the "legal burden of proof" is determined by the legal cases which each party presents. The "legal burden of proof" (unlike the "evidential burden of proof") does not shift (see decision T 301/95, OJ 1997, 519, point 6.2.3 of the Reasons). Whether the burden is discharged or not is assessed by the board in accordance with the appropriate standard of proof on the basis of all the evidence before it. If the party bearing the "legal burden of proof" fails to demonstrate to the required degree the fact(s) on which its legal case rests, the board has to decide against that party. There is no shift of the legal burden of proof in the appeal proceedings. Although an appellant must argue on appeal why the contested decision was wrong, this does not result in a shift of the legal burden of proof on the substance (see decisions T 1210/05, point 2.3 of the Reasons and T 1608/13, point 3.1 of the Reasons).

The legal burden of proof lies with the opponent to establish that the claimed invention lacks an inventive step. The opponent must therefore set forth the state of the art which makes the claimed invention obvious to the person skilled in the art. If, in support of an inventive step, a patent proprietor alleges that the claimed invention has advantageous properties or effects, then the legal burden of proof for the alleged improvement over the prior art rests upon them (see decision T 97/00, point 3.1.6 of the Reasons).

25. The proprietors submitted that the improved properties of antibody 20G7 compared to antibody 24C5 were demonstrated by examples 7, 8, 10 and 13 to 15 of the patent.

26. Of those examples, only examples 8 and 10 are relevant for determining the effect of the difference because they compare both antibody 20G7 and antibody 24C5 directly.

26.1 The examples test the binding to BNP(1-32) and proBNP(1-108), respectively, of three different antibodies, including the antibodies 20G7 and 24C5, in a sandwich-ELISA format using rabbit polyclonal antibody L21016 and hinge 76 antibody, respectively, as capture antibodies.

As shown in Table 3 relating to example 8, antibody 20G7 linearly detects BNP(1-32) at concentrations ranging from 20 to 10 000 pg/ml (see also Figure 5) whereas antibody 24C5 does not.

As shown in Table 5 relating to example 10, antibody 20G7 linearly detects proBNP(1-108) at concentrations ranging from 20 to 10 000 pg/ml (see also Figure 6) whereas antibody 24C5 does not.

Comments in the patent on the results of examples 8 and 10 are that the antibody 24C5 "behave[s] quite differently from the 20G7 antibody", that "20G7 is much more suitable than the 24C5" antibody in the assay formats used, and that antibody 24C5 is "not very effective or not at all effective in detecting BNP(1-32) and proBNP(1-108), even at high concentrations of the analyte".

27. According to the proprietors, the results in document D28 confirmed that the antibody 20G7 displayed better reactivity towards BNP(1-32) than the antibody 24C5 when no capture antibody was used. However, since the experimental set-up in document D28 is not a sandwich-ELISA, it has not been further considered by the board (see point33. below).

28. The opponent submitted that the results of examples 8 and 10 were not suitable to demonstrate the superiority of antibody 20G7 and pointed inter alia to documents D1, D11 and D32. In this context, document D33 provided uncontested evidence that the antibody used in the experiments disclosed in documents D11 and D32 was the same as that used in the patent.

29. Document D1 discloses that "[t]he antibody combination 50E126-32[capture]-24C511-22[detection] manifested the highest detection limit in 1-step sandwich IFA with both synthetic and endogenous antigens ...".

Inter alia, document D11 discloses data (see Figure 4) from a sandwich immunoassay with BNP and proBNP using antibody 50E1 as the capture antibody and 24C5 as the detection antibody. The results show that the 24C5 antibodies "recognize with a very good performance both BNP and proBNP (detection limit is below 0.5 pg/mL)".

Document D32 compares the detection characteristics of antibodies 20G7 and 24C5 towards BNP(1-32) and proBNP(1-108) in a sandwich-ELISA assay using antibody 50E1 as the capture antibody. It discloses that "[m]ab24C5 and mAb20G07 behave quite similarly".

Hence, all three documents demonstrate that antibody 24C5 is very effective at detecting BNP(1-32) and proBNP(1-108). Moreover, document D32 shows similar detection properties for antibody 24C5 and antibody 20G7.

30. Consequently, there seems to be a contradiction between the detection characteristics of antibodies 20G7 and 24C5 disclosed in the patent and those disclosed in documents D1, D11 and D32.

31. The sandwich-ELISA assays in the patent and in documents D1, D11 and D32 were carried out with different capture antibodies. The specificity of the capture antibody determines which parts of the captured molecule are accessible for the detection antibody. Hence, the differences in the detection characteristics could be attributed to the different assay conditions.

32. As submitted by the opponent with reference to the proprietors' submissions in the opposition proceedings, the proprietors have accepted that assay conditions may influence an antibody's detection characteristics:

"The Opponent also contradicted the statement of the Patentee according to which 'the two commercial antibodies 24C5 and 26E2 are not very effective or not at all effective in detecting BNP(1-32), even at high concentrations of the analyte'.

We wish to point out to the Opponent that this statement was made in the context of a specific immunoassay using the L21016 rabbit polyclonal antibody ...

As well-known from the skilled person, different results can be obtained in immunoassays using detection and capture antibodies according to the capture antibody used. This aspect is by the way confirmed in D1 which indicates that a specific antibody combination (50E1 and 24C5 antibodies) enabled obtaining a good detection of BNP (page 868, left column, §2).

The results presented in Example 5 of the patent demonstrates that, when using a different capture antibody than the 50E1 antibody such as the BioRad capture antibody L21016 antibody, the 24C5 and 26E2 antibodies are not very effective in detecting BNP(1-32). There is thus no contradiction between the results of D1 and D6 with the 24C5 and 50E1 antibodies and the results of the Patent with the 24C5 and L21016 antibodies. They are only results obtained using different experimental conditions."(Emphasis in the original; see page 12, last point of the opponent's statement of grounds of appeal together with paragraph 3.4 of the proprietors' submission of 22 December 2015.)

33. On the basis of the evidence on file, the board cannot conclude that antibody 20G7 is generally superior to antibody 24C5 in detecting BNP(1-32) and proBNP(1-108).

34. Consequently, the objective technical problem is formulated as providing alternative antibodies capable of binding to both BNP(1-32) and proBNP(1-108).

Obviousness

35. In the board's view, a person skilled in the art starting from the closest prior-art antibody 24C5 would have been able to provide alternative antibodies capable of binding to BNP(1-32) and proBNP(1-108) using routine methods. Under the case law of the boards of appeal in these circumstances, the claimed subject-matter, i.e. antibodies, is obvious (see e.g. decisions T 735/00, point 26 of the Reasons; T 187/04, point 11 of the Reasons; T 511/14, points 3 and 5 of the Reasons; T 605/14, points 23, 24 and 26 of the Reasons). Therefore, the subject-matter of claim 2 does not involve an inventive step (Article 56 EPC).

Order

For these reasons it is decided that:

1. The decision under appeal is set aside.

2. The patent is revoked.