IP Information & News

Admissibility of prior use evidence

Dr Terence Broderick

By Dr Terence Broderick

Patent Attorney

In third party proceedings, a common strategy to challenge the validity of a patent is to demonstrate that the invention has been used in public before the filing date of the patent. If this can be shown, then the patent may be declared invalid. Demonstrating public prior use can often involve witness statements which can be presented as evidence during the third party proceedings. In case T 564/12, the EPO has recently provided guidance on the admissibility of prior use evidence in the form of a witness statement, the late filing of such a witness statement and the calling of witnesses based on witness statements.

The case relates to an appeal from a decision of the opposition division to maintain EP1667541 in amended form. The opponent (referred to as the opponent-appellant in the decision) filed a large amount of evidence showing public prior use of two products, ‘Kombilock’ and ‘Dubbellock’, which were alleged to fall within the scope of the claims of EP1667541.

The evidence filed included three affidavits, referred to in the decision as D19, D20 and D28, which were filed in support of the public prior use of Kombilock and Dubbellock.

Admissibility of public prior use

The proprietor argued that the public prior uses described in D19 and D20 should not be admitted, as the content of D19 and D20 contained too much ambiguity. It is generally accepted that in order to demonstrate public prior use, the questions ‘what was disclosed?’, ‘when?’, ‘where?’ and ‘under which circumstances?’ need to be answered.

One of the reasons offered up by the proprietor as to the lack of admissibility of the public prior use described in D19 and D20 is the length of time between the alleged prior use and the date that the affidavit was taken — a period of eight years — as it would not be reasonable to remember something to the required degree of clarity over such a period of time.

The EPO accepted that it was possible that memory lapses may have happened, but also accepted the prior use, as the other evidence provided by the opponent would have ‘jogged’ the memory of the witness. Additionally, the EPO also allowed the other evidence filed in support of the public prior use to be used to resolve some of the other ambiguities in the content of D19 and D20. Whilst the EPO did seem to accept that eight years is a long time over which to clearly recite a public prior use, it is possible to use other supporting evidence to paint a ‘consistent picture’ of the prior use.

Late filing of witness statement

The proprietor claimed that D19 and D20 should not have been admitted into the proceedings as they were filed in April 2011 whilst the initial notice of opposition had been filed in January 2008. However, no other reasons were offered as to why the evidence should not be admitted into the proceedings. The opposition division based its decision on this evidence, so had clearly admitted it into the proceedings. The EPO rejected the request of the proprietor for D19 and D20 to be removed from the proceedings stating explicitly that “they appear to have been discussed at the oral proceedings [before the opposition division] without challenge from the proprietor”. The EPO also added that the proprietor did not challenge the admissibility of D19 and D20 in the written opposition proceedings and indeed discussed their relevance.

Whilst it may be possible to challenge the admissibility of a late filed witness statement, such a request must be filed as soon as possible. In this instance, the EPO appears not to have been impressed with what seems to be a late request, after the proprietor realised just how relevant D19 and D20 were to the validity of the claims of the patent in question. Calling of witnesses The proprietor also submitted that, in view of the ambiguity in the public prior uses described in D19 and D20, the author of D28 should have been called to appear as a witness. The proprietor’s submissions, however, were absent any reasoning surrounding which parts of D28 were alleged to be inconsistent or require verification. Additionally, the appeal proceedings were the first time that the proprietor had raised any doubts as to the content of D28, or requested that the author of D28 should be called. The EPO subsequently rejected the request to call the author of D28 as a witness for the above reasons.


Case T 564/12 provides a comprehensive analysis of the way in which the Technical Board of Appeal looks at witness statements and requests to call witnesses. The EPO accepts that memory lapses will happen in the drafting of a witness statement, but acknowledges that other evidence can be used to fill in the gaps in order to build a consistent picture of a public prior use. That being said, what is perhaps more important here are the teachings in respect of the late filing of evidence and the calling of witnesses. The proprietor clearly left it too late to request that D19 and D20 be removed from the proceedings and only seemed to make the request after their relevance had become apparent (when a decision had been based on those documents). Similarly, the decision makes it clear that a request for a witness to be heard must be substantiated, well founded and made as early as possible in the proceedings. A party cannot just expect a witness to be called upon request without good reason.

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