9.2. Consequences of a strong or weak presumption for sufficiency of disclosure

The board in T 63/06 (see "Headnote") agreed that the opponent generally bears the burden of proving insufficiency of disclosure. When the patent does not give any information as to how a feature of the invention can be put into practice, only a weak presumption exists that the invention is sufficiently disclosed. In such a case, the opponent can discharge his burden by plausibly arguing that common general knowledge would not enable the skilled person to put this feature into practice. It is then up to the patent proprietor to prove the contrary, i.e. that the skilled person's common general knowledge would enable the skilled person to carry out the invention. As set out in the previous section, see the findings of T 1076/21 regarding the overview and interpretation of the case law T 63/06 and the related issues.

The board in T 1171/16 made it clear that T 63/06 did not conclude that, for the burden of proof to be shifted, it was necessary for the patent not to give any information whatsoever as to how a feature of the invention could be put into practice.

The board in T 61/21 stated that whether a strong or weak presumption of sufficiency exists must be considered on the facts of each individual case.

T 2176/21 refers briefly to a basic principle summarised by T 1076/21 while also touching on the scope of other principles deriving in particular from T 63/06. As a rule, the appellant (as the opponent) bears the burden of proving insufficient disclosure (see T 1076/21). In addition, a weak presumption as per T 63/06 has to be substantiated and any point of reference demonstrated. It does not follow from T 63/06 that the absence of an example automatically implies a weak presumption or that any weak presumption would automatically be rebutted. In the case at issue, the appellant had not actually presented or demonstrated any specific circumstances implying a weak presumption of sufficiency or set out how this might be rebutted in a second step. No such circumstances were apparent either.

For explanations of the application of T 63/06, see for example T 338/10, in which the board found that the opponent's reasoned arguments had shifted the burden of proof, and, to the same effect, T 518/10. see T 792/00, point 9 et seq. of the Reasons (burden of proof in case of a hypothetical experimental protocol). See also T 491/08; T 347/15; T 1845/17 (ambiguous parameter); T 2218/16 (gene therapy of motor neurone disorders – scAAV9 vector) with detailed reasons.

The board in T 59/18 the respondents (opponents) had convincingly argued that the term "relaxation ratio" having the meaning intended by the appellant was not to be found in textbooks and did not represent common general knowledge, the burden of proof for establishing sufficiency was clearly on the appellant/patent proprietor.

In T 2119/14 (unusual parameter) the board, referring to T 63/06, held that the existence of an undue burden resulted from the almost infinite number of coating compositions that fell under the structural definition given in claim 1, and the established absence of a teaching in the patent in suit as to how select in an appropriate and straightforward manner the components of the coating composition so as to meet the unusual parametric requirement of claim 1. As a consequence, the onus of proving that the preparation of the coating compositions over the whole scope for which protection was sought did not necessitate an undue amount of work for the skilled person rested with the patent proprietor (here: appellant).

The board in T 2401/19 noted that when the patent does not give any information as to how a feature of the invention could be put into practice, only a weak presumption existed that the invention was sufficiently disclosed. In such a case, the opponent could discharge its burden of proof by plausibly arguing that common general knowledge would not enable the skilled person to put this feature into practice.

In T 557/22 the board found the appellant (opponent) was correct when noting that the specification did not teach how the parametric requirement was to be achieved. The specification did not provide the skilled person with a set of instructions indicating how to select the monomers and their relative amounts. It did not even provide a single example. Evidence that the parameter was usual in the art or that suitable common general knowledge was available to the skilled person in order to fill the gap was also not submitted by the respondent. The board decided that a weak presumption that the invention defined in claim 5 was sufficiently disclosed (and conversely a strong presumption for a lack of sufficiency of disclosure) resulted from the absence of any teaching in the specification relating to the measurement of the unusual parameter, the means to achieve the parametric value defined in said claim and an example meeting the condition. Even if one agreed with the respondent that the parameter defined in claim 5 could be easily measured, this would not mean that the skilled person would be in the position to determine which steps had to be taken in order to fulfil the parametric requirements. Although the respondent's argument that the specification would comprise plenty of teaching to work the invention might be valid for independent claim 1, on which claim 5 referred to, this was not true for the invention defined by the terms of claim 5. The respondents allegation of a lack of successfull objection was not persuasive. In the present case, the serious doubts arose from the fact that no teaching at all was provided in the specification and the absence of any further indication, or evidence in this respect, as to what the skilled person would do in order to fulfil that additional condition with a reasonable amount of experimental work.

A further example of a verifiable fact casting doubts on sufficiency of disclosure is given in T 2038/19 (water-absorbent resin particles), applying T 63/06.