The patent relates to a grain-oriented electrical steel sheet having excellent magnetic characteristics and coating adhesion.
Claim 1 as granted comprised a coating layer A on the steel side and a coating layer B formed on a surface side mainly composed of glass.
Dependent claim 4 mentioned the following parameter: “a coating weight of the coating layer A on the steel sheet side is 1.0-3.0 g/m2 (both sides) as converted to oxygen”
Brief outline of the file
The patent was revoked for lack of sufficiency by the OD and the proprietor appealed.
The board held that the invention was sufficiently disclosed, set the decision aside, and remitted the case to the OD for further prosecution.
The case is interesting for the considerations of the board about the difference between the “burden to substantiate a case” from the “burden of proof on the substance“when it comes to sufficiency.
The opponent’s position
It was not possible to reproduce the invention reliably or with any certainty from the parameters disclosed in the examples. Although there were no differences between the manufacturing processes, some samples fell within the scope of the invention while others did not. For example, samples 1, 6 and 11 of Example 1 were carried out with the same manufacturing process but the achieved product properties were significantly different, even to the extent that sample 11 fell outside the claimed range.
The skilled person was thus confronted with an undue burden to experiment with various coating weights, without any guidance on how to do so.
Due to the unusual parameter in claim 4, there was a weak presumption of sufficiency of disclosure. It was not clear how the conversion to oxygen could be established or how it could be measured.
The OD had already been convinced by the reasoned arguments provided by the opponent. There was no need to provide evidence. Since the OD revoked the patent, in accordance with T 585/92, the burden to provide proof that the patent was sufficiently disclosed shifted to the proprietor.
The proprietor’s position
The examples did not show inconsistent results. Paragraph  of the description stated that the coating weight of layer B, the glass layer, was varied. The variation in the results originated from the varying of the coating weight of layer B.
The qualitative causal relationship between the coating weight and the resulting tensile stress formed part of the skilled person’s common general knowledge, and finding suitable values for adjusting the coating weight was an ordinary task that could be conducted without undue burden.
In opposition, the opponent did not present verifiable facts able to refute sufficiency of disclosure.
T 585/92, referred to by the opponent, was an isolated decision which had to be assessed in view of the underlying case. In the case at issue, the burden of proof did not shift to the proprietor since the patent had been erroneously revoked.
The board’s position
On the basis of an in-depth analysis of the relevant case law, the board has concluded that the burden of proof regarding the facts, arguments and evidence on the substance (which initially lies with the opponent) does not shift to the proprietor just because the patent has been revoked due to an alleged insufficient disclosure.
Only if there are serious doubts, substantiated by verifiable facts, may an application or a patent be objected to for insufficient disclosure, cf. T 19/90, Reasons 3.3.
If a material fact is not or cannot be proven, a decision is taken on the basis of who bears the relevant burden of proof. The fact that the real position cannot be established is to the detriment of the party which bears the burden of proof for this fact, among other things because the other party is given the benefit of the doubt.
After the grant of the patent, i.e. after the end of the examination proceedings, a legal presumption exists that the patent meets the requirements of the EPC. In an opposition based on the ground of Art 100(b), it is the opponent who initially bears the burden to prove that the patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a skilled person.
However, this presumption can be rebutted. The weight of the submissions required to rebut the presumption depends on its strength. A strong presumption requires more substantial submissions than a weak one.
In the context of the ground of opposition of lack of sufficiency of disclosure, the strength depends on the way the invention is disclosed in the patent, cf. T 63/06, Reasons 3.2.1 and 3.3.1; T 55/18, Reasons 1.2.
Often both aspects are together referred to as the burden of proof. This might have led to the misconception that any decision finding insufficiency would lead to the burden of proof being shifted to the proprietor.
However, when distinguishing the “burden to substantiate a case” from the “burden of proof on the substance” it can be clearly deduced from the case law that after a decision by the OD allowing an objection of insufficiency, it is down to the proprietor to substantiate on appeal why that decision is wrong.
The “burden of proof on the substance“, and in consequence the benefit of the doubt, however, is only shifted when the OD’s assessment that the presented facts, arguments and evidence were sufficient to discharge the opponent’s burden of proof turns out to be correct.
An appeal case need not necessarily be substantiated by submitting facts and evidence that counter the arguments and evidence presented by the opponent.
It may also be substantiated by submitting why the OD’s reasoning on insufficiency was flawed and why the burden of proof on the substance still lies with the opponent.
This is also in line with decision T 585/92 referred to by the opponent, T 585/92 merely states that the appellant bears the burden to substantiate the appeal. It does not imply that the decision under appeal reversed the burden of proof on the substance.
In all reviewed cases, the respective boards assessed whether or not the opponents had discharged their “burden of proof on the substance” independently of the “burden to substantiate the appeal“.
The board distinguished the following situations
- Successful discharge of the burden of proof on the substance by submitting experimental data
2. Successful discharge of the burden of proof on the substance without experimental data, but with reasoned arguments
The board referred to T 188/18, Reasons 3.21, T66/07, Reasons 7, T 428/21, Reasons 1.4; T 262/11, Reasons 3.4; T 347/15, Reasons 2.2. In T 325/13, Reasons 2.4.8 and 2.5.8, the board even considered that there was no need for the opponent to provide further evidence because the deficiency was plausible from the cited prior art and the simple physiochemical context. Under this heading, the board cited further decisions dealing with the topic.
3. Reasons other than a misjudgement on the substance
An appeal against a revocation of a patent for insufficient disclosure need not be based on the submissions of counter-evidence by the proprietor, as can also be seen in cases where the OD’s decision was set aside.
In many cases the board based its decision not on new evidence but on other arguments why the impugned decision was erroneous.
The board referred to T 1596/16, Reasons 2.2 and 2.3, T 1002/20, Reasons 2.4; T 55/18, Reasons 1.2 and 2.2; T 720/17, Reasons 2.1; T 430/15, Reasons 3; T 355/15, Reasons 6.7.2 to 6.7.4; T 1052/13, Reasons 8.10; T 1746/12, Reasons 6.3.2 to 6.5; T 2006/08, Reasons 4; T 499/00, Reasons 1.10.
In T 942/18. Reasons 2.2 to 3.6, the proprietor successfully showed that the OD’s decision had not been sufficiently reasoned within the meaning of R 111(2).
Substantiation of the appeal in the case in hand
The case at issue is similar to T 1596/16. It is disputed whether or not the guidance given in the patent is sufficient for producing the clad material and whether or not the parameters characterising layer A according to claim 4 can be established. Simple physiochemical considerations, like in case T 325/13 referred to above, cannot resolve this dispute.
For the board, the description of the patent does provide guidance. There is no reason to disregard or doubt it from the outset. The opponent did not submit evidence to prove that the guidance disclosed in the patent was insufficient for carrying out the invention, cf. T 1596/16, Reasons 2.2 and 2.3.
The OD thus could not base its decision on verifiable facts as required by established case law. Sufficiency of disclosure therefore cannot be denied. The board further referred to Case Law Book, 10th ed., Chapter II.C.9; T 499/00, Reasons 1.10; T 2006/08, Reasons 4, T 1002/20, Reasons 2.4.
The opponent argued that the coating weight for layer A as defined in claim 4 was an unusual parameter or was not able to be measured.
There is no indication that these aspects were already raised in the opposition proceedings. The decision under appeal consequently does not cover them.
There is no evidence on file showing that the guidance provided in the patent is insufficient, e.g. because identical coatings in terms of manufacture and thickness imparted substantially different tensions on the steel sheet.
Irrespective of the admission of these arguments under Art 12(6) RPBA21, the opponent did not show that the parameter for defining layer A in claim 4 was an unusual parameter or not able to be measured.
Since the opponent did not provide the evidence required for substantiating serious doubts; it did not discharge its burden of proof on the substance.
Since the parties make contradictory but unsubstantiated assertions concerning facts, the proprietor is given the benefit of the doubt, cf. T 72/04, Reasons 3.
It is not so frequent that a board takes the bother to have such wide look at the case law on a specific topic, here sufficiency of disclosure, and the various ways it can be dealt with.
This is a service to the users of the EPO going way further than a bare minimum of reasoning in order to dispose of the case as quickly as possible. This point needs to be emphasised.
As a summary there are two ways to deal with sufficiency
- With experimental data, which is the most common way. Arguing a lack of sufficiency without any experimental data boils in general down to a mere allegation, or even a hidden clarity objection.
- Without experimental data, when the opponent makes it plausible that common general knowledge cannot supplement the missing information. In other words, the argumentation has to be solid,cf. T 100/15 or T 275/16. When a parameter cannot be measured, even then experimental data might be required.
An unsubstantiated allegation is insufficient to cast doubt on the presumption that the invention is sufficiently disclosed, see T 1163/12, Reasons 3.3.
The breadth of an expression is more a matter concerning the clarity requirement of Art 84 rather than a ground for opposition under Art 100(b). The mere fact that a term is broad does not prevent a skilled person from carrying out the invention, cf. T 2182/11, Reasons 2.
When appealing a decision on lack of sufficiency, it has to be distinguished between the “burden to substantiate a case” from the “burden of proof on the substance“. The mere revocation of the patent by the OD is, as shown by the present case, not always sufficient for a reversal of the onus of proof.
The board also reminded that in case of contradictory assertions by the parties, whereby the Office is not in a position to decide, then the benefit of the doubt goes to the proprietor. Further to T 72/04, it is also possible to refer to T 808/05 or T 1598/15.
The legal presumption of validity of a granted patent
It can be agreed with the board that there exists a legal presumption that a patent meets the requirements of the EPC once it has been granted.
When looking at published decisions after appeal in opposition, only 18,7% of the oppositions were rejected, but the patent was revoked in 48,1% of the cases or the patent maintained in amended form in 33,2% of the cases.
Serious doubts about the presumption of validity of a granted might thus be raised. It is clear that oppositions are only filed when a patent is disturbing an opponent, be it for the risk of already infringing or infringing in the future. It remains nevertheless that it is just in case of possible litigation that a patent needs to be strong and valid. If a patent crumbles at the first attack in opposition, one wonders why it has at all been granted.
The present case is also to be seen among the 50%+ of decisions of ODs which have been set aside by a board.