The EPO Boards of Appeal recently decided a case involving food products for infants, where it considered that the requirement “up to the hilt” in relation to prior art equated to “beyond reasonable doubt” rather than “absolute certainty”.

We previously discussed decision T 1410/14 from a Technical Board of Appeal at the European Patent Office (EPO), in which the Board had to decide on the prior art effect of an alleged, but very brief, public prior use: did the length of frequency of a public disclosure affect its status as prior art?

In the recently issued decision T 2451/13, a different Technical Board had to decide a related issue concerning prior art: whether a document referred to as D16, and marked as copyright 2002, had been made available to the public before 2006. Additionally, the Board had to decide whether to admit D16 into the proceedings (ie whether to allow arguments to be based on it), since D16 had been filed for the first time at the appeal stage.

The patent in question related to food products suitable for administration to an infant that serve the purpose of stimulating the consumption of fruit and vegetables later in life – so called sensoric imprinting. The patent had been opposed at the EPO after grant, with the opposition proceedings at first instance ending in revocation of the patent. The patent proprietor then appealed.

At first instance, reliance had been made by the opponent on a document, referred to as D2, which like the patent is concerned with sensoric imprinting. It is clear that D2 was considered highly relevant by the Opposition Division tasked with reaching the appealed decision. However, the Opposition Division held that the date of disclosure of D2 had not been proven adequately by the opponent. In particular, it held that although D2 bore a copyright date of 2005 – before the priority date of 2006 –, it was held not to be proof of a disclosure in 2005, following the logic of an earlier Technical Board of Appeal decision on this point (T 1257/05).

It was when responding to the proprietor’s appeal that the opponent filed D16, arguing that this was in reaction to Opposition Division’s decision that D2 had not been proven to be prior art. The proprietor argued that D16 should not be admitted, on the basis that it led to new arguments, and because the proper way to address the Opposition Division’s decision that D2 was not citable prior art was to file evidence rebutting this finding.

The Technical Board disagreed, contending that D16 was not filed to raise a new inventive step attack but, rather, to show that the teaching of D2 was publicly available before the priority date of the patent. It noted that the disclosure of D16 is very similar to that of D2 but that the marked copyright date of D16 (2002) was much earlier than the 2005 date for D2. Moreover, it was considered that it was as appropriate to file evidence that the teaching in D2, rather than D2 itself, was available to the public before the priority date.

The proprietor argued, again with reference to T1257/05, that the copyright date on D16 did not on its own substantiate its status as prior art. Additionally, it argued that the applicable standard of proof had to be the so-called “up to the hilt” standard. This is a well-recognised standard of proof where evidence in support of an alleged prior use lies outside the control of a proprietor. The Board agreed with the proprietor insofar as the proper standard of proof was to be up to the hilt, noting that because D16 originated from a company (Gerber), which was now a subsidiary of the opponent, all evidence as to its publication date was essentially in the hands of the opponent.

Arguably the key point from this case is the Board’s consideration of what was required from the opponent in order to demonstrate, up to the hilt, that D16 had indeed been made available prior to the priority date in 2006. It considered and commented on a number of earlier decisions from the Technical Boards, including the seminal case T 472/92 in which the “up to the hilt” standard was first referred to.

Although it noted that T 472/92 did not specify precisely the conditions to be filled in order for evidence to be proven according to this standard, the Board observed that, in T 472/92, it is stated that “its conclusions were based on ‘… an extremely high degree of certainty’, which is thus clearly the yardstick – rather than ‘absolute certainty’ – for ‘up-to-the hilt’ proof”. The Board also considered other relevant cases in which the term “up to the hilt” is essentially equated with “beyond reasonable doubt”.

Notwithstanding the argument based on T 1257/05 about the 2002 copyright date not substantiating D16’s status as prior art, the Board stated that, since D16 was addressed to parents, giving them instructions on how to feed their infants, “it would be contrary to life experience to assume that D16 was not published but rather kept by Gerber in the drawer for about 4 years, i.e. until at least (after) the priority date of the patent”. It found this view to be corroborated by a further document, a published jabber advertisement from 2002 containing some material common to D16. It concluded that it was “quite clearly beyond reasonable doubt that D16 was published before the priority date of the patent”.

Although decisions of the EPO’s Technical Boards of Appeal are only binding in connection with the decision being appealed, the Board noted for completeness that its finding of D16 as prior art was not at variance worth T 1257/04. In that case, the issue was whether showing a date “9/94” could be assumed to have been printed within five months. As well as noting that the four-year period within which D16 needed to have been made available to the public to be relevant prior art was much longer, it also pointed out that there were two other cases in which publication was held to have taken place within seven and 18 months of dates indicated on the respective documents.

Whilst the case (which is available on the EPO's website) is interesting for other reasons, and thus worthy of study in full, the take-home message is the practical approach taken, and advice given, by the Board to the problem of proving evidence “up to the hilt”, this equates to “beyond reasonable doubt” rather than “absolute certainty”.