T 0063/06 du 24.06.2008

The burden of proof generally lies upon an opponent to establish insufficiency of disclosure.

When the patent does not give any information of how a feature of the invention can be put into practice, only a weak presumption exists that the invention is sufficiently disclosed (see Reasons 3.3). In such 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.

The patent proprietor then has the burden of proof for contrary assertion that common general knowledge would indeed enable the skilled person to carry out the invention.