The patent proprietor filed an appeal against the decision of the Opposition Division (OD) to maintain the patent in amended form.
The OD had admitted late filed documents D6 to D8 and found the main request to lack novelty over their disclosures. It considered that the period of six weeks and three days was sufficient for the patent proprietor to file counter-evidence.
The Board did not see things this way:
*** Translation of the French original ***
[3.1] Document D6 and the results of trials reproducing and characterising the catalyser disclosed therein (documents D7 and D8) have been filed by the [opponent] about six weeks before the oral proceedings (OPs) before the OD. The [opponent] has pointed out, based on these documents, that the claimed subject-matter lacked novelty. On the day of the OPs, the European patent has been revoked based on this new evidence. The [patent proprietor] has pointed out that in these circumstances he had not been granted the right to be heard because he had not had the time to respond to the new evidence by carrying out his own counter-evidence trials (contre-essais).
[3.2] According to A 113(1), the decisions of the EPO may only be based on grounds or evidence on which the parties concerned have had an opportunity to present their comments.
In this regard, it is not sufficient that a party has had knowledge of the arguments and evidence used against it, but it also must have had the opportunity of responding by preparing an appropriate defence.
[3.3] In the present case, the [patent proprietor] undeniably has been confronted with a new factual situation, comprising a new document and experimental results challenging the novelty of the claimed subject-matter, six weeks before the OPs before the OD. However, the OD, after having admitted this new evidence presented shortly before the OPs into the proceedings, has not given the [patent proprietor] the opportunity of responding in an appropriate way, i.e. as desired by the [patent proprietor], by carrying out trials in order to show that the catalyser disclosed in document D6 did not fulfil the requirements of the claims under consideration.
[3.4] The OD has argued that the six weeks remaining before the OPs were sufficient for carrying out those trials although the [patent proprietor] had pointed out that this was impossible because there was not enough time.
In the present circumstances the Board is unable of making statements on how much time was necessary to carry out comparative trials. However, it notes that as far as periods are concerned, R 132(2), for instance, stipulates that a period specified by the EPO shall be neither less than two months and may be extended upon request. As a rule, the period for responding to substantive questions is set to four months and extended to six months upon request, and requests for longer extensions may be allowed in exceptional circumstances, such as the need to provide experimental trials (see the Notice of the Vice-President of DG2 dated February 28, 1989, OJ 5/1989, 180 and the Guidelines [E-]VIII 1.2 and 1.6).
These time limits, even though they do not apply in the present case (R 116(1)), show that a party cannot be required to file comparative trials within a period that does not exceed six weeks.
Moreover, the [patent proprietor] had explained that he could not carry out the trials in time because, among other things, his research laboratories were closed during the period under consideration. The OD has asserted, without any further justification, that this argument was not relevant. The Board, however, considers this argument to be completely justified because obviously it is impossible to carry out trials when the laboratories where they are to be performed are closed.
As a consequence, it was impossible to carry out the trials between the moment when the [patent proprietor] had had knowledge of documents D6 to D8 and the date of the OPs. Consequently, the Board comes to the conclusion that the OD, when basing its decision on the new documents without allowing the [patent proprietor] to respond by means of counter-evidence which he considered to be necessary, has not granted him the right to be heard, in violation of A 113(1), which amounts to a substantial procedural violation.
 The [opponent] points out that the [patent proprietor] had never asked for a postponement of the OPs in order to be able to present counter-evidence.
However, the [patent proprietor] had requested the OD not to admit the late filed documents D6 to D8 into the opposition proceedings because, inter alia, he was unable of carrying out comparative trials and because his right to be heard was violated, which goes beyond postponing the OPs. Therefore, this argument of the [opponent] has to be dismissed.
 As a consequence, the impugned decision has to be set aside and the case has to be remitted to the OD for further prosecution (A 111(1)). The reimbursement of the appeal fee is ordered because the appeal is allowed and because the reimbursement is equitable due to the substantial procedural violation, i.e. the violation of the right to be heard (R 103(1)(a)).
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