9.5. Burden of proof shifted to the patent proprietor

This section sets out several example cases in which it was decided that the burden of proof had shifted to the patent proprietor. Please also refer to the longer summary of T 1076/21 in the introduction to chapter II.C.9. and the section regarding the application of the case law T 63/06 in chapter II.C.9.1.

In T 1886/19 the board found that owing to the weak presumption of sufficient disclosure (lack of any information in the patent application to put the invention into practice; T 3012/18) and the evidence furnished by the opponent (respondent), the opponent had discharged the initial burden of proof and it had now shifted to the patent proprietor (appellant), which had failed to prove that the invention could be carried out without undue burden.

In T 1187/20 the board found that the burden had shifted to the patent proprietor (respondent) to prove how the contradictions in claim 1 could be resolved. Among other things, the board stated that under the circumstances, the opponent did not have to provide any additional experimental evidence to substantiate the serious doubts; there was a weak presumption of sufficiency, with reference to T 63/06. The board also stressed that not only was there uncertainty about the limits of the claim, but it was also impossible to determine the crux of the invention and how the compound of claim 1 was determined.