IP Cases & Articles

T 0261/15 - novelty of overlapping ranges

In T 0261/15, a European Patent Office (EPO) Board of Appeal upheld a decision of the Opposition Division maintaining European patent No. 2247764 (British Steel Ltd) as granted. Significantly, the Board of Appeal decided that the limit values of a known range, although explicitly disclosed, are not to be treated in the same way as the examples. As a result, the Board of Appeal found that the claimed composition, although overlapping with the generic composition disclosed in the prior art, was novel.

Background to T 0261/15

EP 2247764 relates to a high-strength pearlitic steel rail which is defined by its composition of alloying elements. More specifically, claim 1 as granted reads: “A high-strength pearlitic steel rail with an excellent combination of wear properties and rolling contact fatigue resistance wherein the steel consists of 0.88% to 0.95% carbon, 0.75% to 0.95% silicon, 0.80% to 0.95% manganese, 0.05% to 0.14% vanadium, up to 0.008% nitrogen, up to 0.030% phosphorus, 0.008% to 0.030% sulphur, at most 2.5 ppm hydrogen, at most 0.10% chromium, at most 0.010% aluminium, at most 20 ppm oxygen, the remainder being iron and unavoidable impurities.”

The patent was opposed by a single opponent on the grounds of lack of novelty and inventive step. In particular, the opponent argued that the granted patent lacked novelty over EP 2006406 (D1).

D1 also relates to a high strength pearlitic steel rail defined by its composition of alloying elements. The composition of claim 1 of the granted patent and the broad composition disclosed in D1 are compared in the table below (in wt%).

Element Claim 1 of granted patent D1 (claims 1, 2, 3 and 6)
C 0.88 - 0.95 0.6 - 1.0
Si 0.75 - 0.95 0.1 - 1.5
Mn 0.080 - 0.95 0.4 - 2.0
V 0.05 - 0.14 0.5 or less
N up to 0.008
P up to 0.030 0.035 or less
S 0.008 - 0.030 0.0005 - 0.010
H at most 2.5 ppm
Cr at most 0.010 1.5 or less
Al at most 0.010
O at most 20 ppm 0.004 or less
Other Cu: 1.0 or less
Ni: 1.0 or less
Mo: 1.0 or less
W: 1.0 or less
Nb: 0.05 or less
Optional - Ca: 0/001 - 0.010

The opponent argued that the granted patent relates to a selection invention but does not satisfy the criteria that the case law has identified for a selection invention.

The case law

The case law on the novelty of selection inventions was developed in particular in T 198/84, which was then summarised in T 279/89. According to T 279/89 a selection of a sub-range of numerical values from a broader range is new when each of the following criteria is satisfied:

  1. the selected sub-range should be narrow;
  2. the selected sub-range should be sufficiently far removed from the known range illustrated by means of examples;
  3. the selected area should not provide an arbitrary specimen from the prior art, that is, not a mere embodiment of the prior description, but another invention (purposive selection).

In the case of overlapping ranges, the Board of Appeal held in T 666/89 that there was no fundamental difference between examining novelty in situations of so-called “overlap” or “selection”. Hence, the same principles should be applied for the assessment of novelty in case of overlapping ranges that are applied in the case of selection inventions. Namely, it has to be determined which subject matter disclosed in a prior art document has been made available to the public.

In decision T 26/85, the board suggested a specific test for determining whether a technical teaching had been made available to the public or not. In particular, the Board of Appeal proposed asking: would the skilled person, in light of the technical facts and taking into account the common general knowledge, seriously contemplate applying the technical teaching of the prior art document in the range of overlap? This question has been adopted in several subsequent Board of Appeal decisions.

Arguments at appeal

At appeal, the appellant (opponent) argued that the claimed composition overlapped with the generic composition of the pearlitic rail disclosed by D1. The appellant argued that:

  1. The ranges for the alloying elements of claim 1 were not narrow in comparison with the corresponding ranges disclosed in D1; and
  2. The claimed range was not sufficiently far removed from the end points of the known ranges.

The latter argument was taken from the Guidelines for Examination, which recites at Part G, Chapter VI, Paragraph 8 that a sub-range selected from a broader numerical range of the prior art is considered novel, if “(b) the selected sub-range is sufficiently far removed from any specific examples disclosed in the prior art and from end-points of the known range”.

The Board of Appeal ruled that D1 does not provide any teaching which would lead the person skilled in the art to seriously contemplate working in the claimed composition. Therefore, the claimed composition was novel over D1.

Reasons for the decision

The Board of Appeal agreed that the claimed composition overlapped with the generic composition disclosed by D1. However, the Board of Appeal noted that since the different alloying elements interact with each other to form precipitates and solid solutions their content ranges are not to be considered in isolation but in combination. Hence, the Board of Appeal ruled that the range of overlap was narrow in respect of the composition of D1.

In respect of the argument according to which a selected sub-range has to be sufficiently far removed from the end-points of the known range, the Board of Appeal noted that it was not aware of any jurisprudence stating this condition in such a general way. The Board of Appeal pointed to the Guidelines for Examination (Part G, Chapter VI, Paragraph 8) which recites this criterion as a condition for acknowledging novelty of a numerical selection under point (ii)(b), however, noted that neither decision T 198/84 nor T 279/89, which are cited in this passage of the Guidelines for Examination, stipulate this condition.

In the Board of Appeal’s view, the limit values of a known range, although explicitly disclosed, are not to be treated in the same way as the examples. The Board of Appeal further stated that the person skilled in the art would not, in the absence of further teaching in this direction, necessarily contemplate working in the region of the end-points of the prior art range, which are normally not representative of the gist of the prior art teaching.

The Board of Appeal ruled that in the present case D1 did not provide any teaching which would lead the person skilled in the art to seriously contemplate working in the claimed composition. Thus, the Board of Appeal decided that D1 was not novelty destroying. The Board of Appeal also found that claim 1 was inventive over the cited documents, therefore, the appeal was dismissed and the patent was maintained as granted.

This decision provides further details on the assessment of novelty of overlapping ranges at the EPO. However, it also provides a subtle caution for those citing the Guidelines for Examination at appeal.

The Guidelines for Examination may develop over time to include elements that were not recited in the original decision upon which the cited section of the guidelines is based. In these instances, as was the case above, the Board of Appeal may not consider the additional elements included in the Guidelines for Examination to be a requirement and may instead rely on the information provided in the original decision.

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