In T 100/15, the board agreed with the patent proprietor's argument that the burden of establishing insufficiency of disclosure lay with the opponent in inter partes proceedings. However, when a patent did not give any information on how a feature of the invention could be put into practice (in this case, the controlled cooling), and the opponent had plausibly argued that common general knowledge would not enable the skilled person to do so, it was for the patent proprietor to demonstrate otherwise.
In T 1299/15, the board held that under established case law the opponent (in this case, the appellant) bore the burden of proving an alleged lack of reproducibility. However, since the patent specification did not describe any embodiment for the adjustment device, the appellant was unable to do so on the basis of such an example and instead could only base its case on attacking the device's plausibility, which was it then did. That shifted burden of proving the contrary to the patent proprietor (in this case the respondent).