A recent decision of EPO Boards of Appeal provides some guidance regarding the standard that a party needs to meet in order to show that a certain document was publicly available at or before a particular date, e.g. before the priority date of a third party European patent. This guidance is most welcome considering that companies often challenge third party European patents on the basis of an alleged prior public use of the claimed invention, and for such companies – as well as for the patent owners – it is essential to understand when the documents showing such alleged prior public use meet the standard to qualify as part of the state of the art and when they do not.

Until now, the established EPO case law stated that the standard of proof for the public availability of documents or information completely falling within the control of one of the parties (e.g. public prior use by the party) is “up to the hilt”, the hilt being the sword’s handle. The expression “up to the hilt”, which is often used to express an act which is carried out to the very limit, completely or with nothing lacking, remained somewhat obscure for parties using the EPC system.

For this reason, the new decision rendered in January 2016 certainly comes as a welcome clarification.

In this case, the Board had to assess the public availability of a commercial brochure bearing a copyright date 4 years before the patent’s filing date. No further proof that the brochure had in fact been distributed to the public, rather than being kept hidden by the opponent, had been provided. The Board reviewed the case law and concluded that the “up to the hilt” corresponds to the standard of “beyond reasonable doubt”, explaining that [i]f the publication date of a document originating from an opponent … is in dispute, the opponent must prove that date ‘up to the hilt’. The yardstick for this proof is that of ‘beyond reasonable doubt’ rather than ‘absolute certainty’”.

Specifically, the Board cited several previous decisions addressing the standard to be met for showing that a certain document had been made available to the public where the related evidence rested only in the hands of one party, normally the opponent relying on such document for invalidating an adverse European patent. Among other things, such case law had held that, where practically all the evidence lies within the power of the opponent, the criterion applied by the Boards should be strict in that there should be a degree of certainty which is beyond all reasonable doubt. The Board also noted that, in cases where only one party has access to information about an alleged public prior use, the case law had tended towards expecting that the public prior use be proved beyond any reasonable doubt, answering the typical questions “What?”, “When?”, “Where?”, “How?” and “To whom?”. The reason for this was identified as lying in fact that the other party, i.e. normally the owner of the European patent, is reduced to merely pointing out inconsistencies or gaps in the chain of evidence.

In the case underlying the new decision of January 2016, the EPO found that the “up to the hilt” standard had to be applied since the document under review originated from a subsidiary of the opponent. The Board thus examined whether the opponent has proven beyond reasonable doubt that the document was available to the public before the priority date of the patent. In view of the document’s content (instructions to parents on how to feed their infants), the Board considered that it would be contrary to life experience to assume that the document had not been published but rather kept undisclosed for about 4 years, also holding that this was corroborated by a further document representing an advertisement by the opponent’s subsidiary predating the priority date and containing the same recommendations to parents and using partly the same pictures. The Board thus held that it was not only more likely than not, but quite clearly beyond reasonable doubt, that the document at stake had been published before the priority date of the patent.

This decision will certainly be most helpful for allowing parties involved in proceedings before the EPO either to meet the required standard when relying on certain evidence or to point out deficiencies in the evidence submitted for reaching that standard.


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