9.4. Burden of proof on the opponent – special cases

In T 347/15 the board endorsed the case law on evidence (Art. 83 EPC) and, having found that the application did not contain detailed information about how to put the invention into practice, applied the reasoning given in T 491/08. In the case in hand, the opponent (appellant II) would have had to perform a large number of costly tests to prove that the invention could not be carried out, whereas a single example from appellant I (patent proprietor) would have been enough to prove that it could. The board concluded that appellant II (opponent) had discharged its burden of proof by submitting comprehensible and plausible arguments giving rise to serious doubts about whether the skilled person could carry out the invention as claimed. That meant it had then been up to appellant I (proprietor) to prove the contrary, i.e. that the invention could be carried out, but it had failed to do so. In particular, the board found that, owing to the lack of information in the patent, carrying out the invention went beyond the usual know-how of the skilled person.

In the field of mechanics in T 500/20 the board said in its Catchword that in claimed inventions that did not involve a range of parameter values or compositions but were directed at a concept expressed in terms of generic structural or functional features of an apparatus or of a method, it was not enough – in order to demonstrate insufficiency – to conceive of an example that fell within the terms of the claim that did not work because it did not achieve the claimed effect fully or at all so that therefore the invention would not be sufficiently disclosed across the entire breadth of the claim. To successively argue insufficiency in a case such as this, a very high burden of proof applied; the party had to demonstrate through cogent argument based on the underlying principles, if necessary supported by evidence, that the claimed concept did not work because it did not achieve the desired effect in any measure or indeed was counter to the laws of nature. Or the party must demonstrate that the disclosure lacked information on an important aspect of the claimed invention, without which the skilled person could not realise the claimed invention without undue burden. The appellant (opponent) failed to present any such arguments.

In T 970/16 (use of the cellulase in laundering process), the board stated that the opponents, which indeed did not file themselves any evidence, discharged their burden of proof by relying on the available evidence X29 (experimental report filed by the patent proprietor) and by plausibly arguing that common general knowledge would not enable the skilled person to realize the disputed benefits. The required technical effect was due in the present case to a hypothetical mechanism not yet being part of common general knowledge as stated in the patent. The skilled person, in view of the unsuccessful results of X29, would be obliged to start a research program.

In T 557/22, in the absence of a proper argumentation relating to the lack of ability of the skilled person to prepare an orthodontic appliance as defined by the terms of claim 6, i.e. according to the alleged ambiguously defined subject-matter, there was no reason for the opposition division to take a position on that issue. Accordingly, contrary to the appellant's (opponent's) view, the contested decision did not lack substantiation with respect to the issue of sufficiency of disclosure of claim 6.