3.12. Burden of proof

The petitioner bears the burden of proving its allegations (R 4/09). However, in R 15/11 the petition was allowed and the Enlarged Board stated that it is not for the party which alleges a breach of its right under Art. 113(1) EPC to prove that it has not been heard (negativa non sunt probanda). It would rather be the task of the boards to draft their own texts in a way that enables the reader, taking into account all documents on file, to conclude that the right to be heard was respected with regard to the grounds on which the decision is based.

In R 4/17 the Enlarged Board considered, in respect of the implausibility of the non-arrival of letters put forward by the other party, that it could not be expected that the petitioner should prove a negative, that is the non-receipt of a letter, or provide a plausible explanation for non-receipt (negativa non sunt probanda).

In R 8/18 the petitioner pointed to decision R 15/11 and the principle of "negativa non sunt probanda", arguing that it was not for the party to prove that it had not been heard. The Enlarged Board distinguished the case in hand from R 15/11. The petitioner in R 15/11 could point to the absence of facts which led to a legal conclusion, namely, the finding that the party had not been heard. In the case in hand the petitioner based its claims on positive facts, namely, the events that were stated to have occurred. Under these circumstances, the Enlarged Board found that the petitioner clearly carried the burden of proof that these events indeed occurred as stated.