T 0516/08 - Old secondary document

T 0516/08

For the decision, click here (published 3 May 2010).

Key points

• What is the relevance if a prior art document cited as secondary document is very old?
• According to T516/08, the age of a document can "only play a role as regards the closest prior art". However, this decision seems to have been one-off. The decision has been cited by only one other decision and not for the aspect at issue; the case is not included in the Case Law Book. 
• The Case Law Book  (I.D.9.7) states: "it would not be obvious to a skilled person to combine an isolated, very old document (i.e. 50 year old document), which had not given rise to a trend in the art and whose teaching ran counter to the present trend, with the document reflecting the closest state of the art (T 261/87, T 366/89, T 404/90)." However, this statement unfortunately does not identify the effect alone - what if the document is old, but not counter to the current trend? 
• In T164/03, the Board held that " Even though D29 was published about 45 years before the priority date of the patent in suit, it already related to light Diesel fuel having a sulphur content of 0.05% and the implication of insufficient lubrication [...]. Further, it appears from D15 that low sulphur content in Diesel fuel was not an issue for the suppliers before the governmental restriction due to environmental concerns took effect in Sweden and Japan in 1992, [...]. Given these circumstances, the skilled person had good reasons to consider the old technology of D29 at the priority date of the patent in suit in 1994, even though it did not play any role in the meantime." This suggests that looking in an old document without good reason can be non-obvious. 
• According to T 1408/04, "age of a document by itself is no reason to exclude a document as representing the closest prior art starting point"
• Note that a 50 year old document can be closest prior art, in particular if it is technically closer to the claim than more recent documents (T 1869/11). 
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T 0516/08 
10. A further argument put forward by the appellant is that the publication dates of documents E1 [closest prior art] and E2 [E2: US 2067998] (1996 and 1937) lay too far apart and the significant time (more than five years) which had elapsed between E1 and the application date of the patent in suit (2001), were a clear indication that the present invention was not so easy to arrive at for the persons skilled in the art.

As regards the age of E2 the Board concurs with the case law in this respect (see Case Law of the Boards of Appeal, 5th edition 2006, Chapter I.D.3.7 [7th edition I.D.3.6 ) that this can only play a role as regards the closest prior art, which is E1, not E2.

[...]

With respect to E2, supporting the missing teaching, having been published 64 years before the application date the Board also concurs with the case law (see Case Law of the Boards of Appeal (supra), Chapter I.D.9.3) that it is not that period that counts, but that between the time at which the problem became apparent and the application date, which in any case cannot be longer than the five years between E1 and the application date, because it was with the package of E1 that the gripping problem emerged in the first place, A period of five years in the field of packaging cannot really be seen as long, particularly as it may result from a variety of causes: for example, there may have been a commercial reason for not adopting this new technique, because the old technique was found satisfactory by the clients and could also be improved in a different way, thus avoiding considerable investment costs involved in the adoption of a new technique on an industrial scale.