T 680/08 – Still The Same?

The present decision contains some rather surprising findings concerning the validity of a claim to priority.

Claim 1 according to the main request read as follows:

1. Method of compounding a multimodal polyethylene composition in a compounding device, wherein

a) the total residence time of the polyethylene composition in the compounding device is at least 3 minutes,

b) the total drive specific energy (SEC) applied on the polyethylene composition is from 0.330 to 0.415 kWh/kg,

c) optionally, a specific cooling energy (SCC) of at most 0.200 kWh/kg is applied on the polyethylene composition,

d) the total specific energy, which is the difference between the total drive specific energy SEC and any specific cooling energy SCC, applied on the polyethylene composition is from 0.220 to 0.330 kWh/kg. 

The value of lower limit for the total drive specific energy (SEC) applied on the polyethylene composition was 0.325 kWh/kg in the European patent application the priority of which was claimed and had been modified to 0.330 kWh/kg when the opposed patent was filed. This change appears not to have been triggered by prior art (the search report for the priority document was positive) and was not even due to rounding up; the patent proprietor later attributed it to “sloppiness” in drafting.

Issues relating to priority

[1] The subject-matter of claim 1 of the main request corresponds to the disclosure in the priority document D0 with the exception of the explicit mention of the value of total drive specific energy (SEC) of 0.330 kWh/kg.

In consequence, in claim 1 of the main request, the only contested issue is the validity of the claim to priority in view of the value 0.330 kWh/kg used as lower boundary of the total drive specific energy (SEC) range of feature b).

Same invention

[1.1] According to A 87(1)(b), a claim to priority can only be validly claimed in respect of the “same invention”.

Claim 1 according to the main request concerns a process whose value of total drive specific energy is constrained to lie within the particular range of values from 0.330 to 0.415 kWh/kg.

The priority document D0 discloses that “in the method according to the invention, the total drive specific energy (SEC) applied on the polyethylene composition is preferably at least 0.325 kWh/kg” and that “the total drive specific energy (SEC) applied on the polyethylene composition preferably does not exceed 0.415 kWh/kg” […].

When filing the patent in suit, the lower bound value of the range of total drive specific energies was therefore increased from 0.325 kWh/kg to 0.330 kWh/kg, i.e. to a value which lies inside the range disclosed in the priority document.

On the basis of this disclosure, the priority, if claimed accordingly, would be valid for methods wherein the total drive specific energy is chosen to be in the range of 0.325 to 0.415 kWh/kg and thus includes all methods whose actual value for the SEC is anywhere within the range of 0.325 to 0.415 kWh/kg, i.e. also for SEC values which were not mentioned explicitly in the priority document such as 0.330 kWh/kg.

However, before a conclusion concerning the validity of the priority can be arrived at, it is necessary to consider the arguments against it.

Technical effect

[1.2] One aspect to be considered is whether the technical effect associated with SEC values from 0.330 to 0.415 kWh/kg differs from the one associated with SEC values from 0.325 to 0.330 kWh/kg.

It was proposed on the part of the [opponents] that when comparing the examples set out in tables 1 and 2 of the patent in suit, differences in applied SEC comparable to the 0.005 kWh/kg increase produce significant differences in properties such as white spot dispersion, gel count and pigment distribution.

However, these examples are not directly comparable, because of additional changes in other parameters, such as residence time and/or the use of different polymers. […] The resulting differences in white spot dispersion, gel count and pigment distribution are therefore not necessarily primarily due to changes in applied SEC. Furthermore, taken as a whole, the examples set out in tables 1 and 2 of the patent in suit show that the claimed processes of compounding multimodal polyethylene are naturally subject to variations in properties such as the number of gels. The Board therefore considers that, on the basis of these examples alone, it is not possible to attribute a given property - such as, for example, the difference in the numbers of gels/kg - directly to a change in SEC alone.

It was also proposed on the part of the [opponents] that in view of figure 2.1 of document D23, an applied energy of 0.330 kWh/kg would bring the tested multimodal polyethylene composition critically close to its decomposition temperature, such that even a small change in applied energy might have a decisive technical effect concerning the thermal destruction, or not, of the multimodal polyethylene composition. The method claimed in the present invention concerns compounding a multimodal polyethylene composition, which process loses its purpose should the composition be thereby heated to destruction. The skilled person would therefore only use the claimed compounding method without operating near the thermal destruction of the multimodal polyethylene composition.

It was further alleged on the part of the [opponents] that no change would be made to the claimed range of SEC values without good reason. However, no such reason or proof of a change in technical effect was supplied.

Furthermore, it was alleged on the part of the [patent proprietor] - and not denied by the [opponents] - that the 0.005 kWh/kg increase in the lower bound value of SEC is allegedly comparable to other sources of natural variations in applied energy such as temperature fluctuations due to the seasons or efficiency variations in mechanical agitators, motors and gearboxes. The Board therefore concludes that there is no proof that the increased SEC lower bound value of 0.330 kWh/kg results in any identifiably other technical effect compared to the technical effect associated with the larger range disclosed in the priority document.

Enlarged Board of Appeal (EBA) Opinion G 2/98

[1.3] It was suggested on behalf of the [opponents] that, in view of the strict requirements set out in the EBA opinion G 2/98, the mere fact that the value 0.330 kWh/kg was not mentioned in document D0 was enough to lose the priority claim for the whole of the subject-matter of claim 1 of the main request.

As the Board has not found any indication in opinion G 2/98 that the EBA explicitly considered the particular case of a process in which a value is constrained to lie inside a range whose lower bound has been marginally moved inwards, the response to the above argument requires a closer look at the reasoning used in that EBA opinion.

In arriving at its conclusions in opinion G 2/98, the EBA took into account possible adverse effects of alternative assessments of the validity of a claimed priority.

In the present case, denying the claim to priority for the subject-matter of claim 1 across the whole range of SEC values would lead to the following adverse effect: A third party could file an application for a process claiming the SEC upper bound value of 0.415 kWh/kg in the interval between the filing of the priority document D0 and of the filing of the application for the patent in suit. Such a document, once published, would form prior art according to A 54(3) for the upper bound value in the patent in suit. The proprietor would therefore be effectively forced to restrict his claim to exclude this upper bound, although he was the first to disclose it in his own priority document D0. The Board considers that this goes against the principle of fairness, as the [patent proprietor] would effectively be punished for increasing the lower bound value - a measure not foreseen anywhere in the EPC.

It was further argued on behalf of the [opponents] that the [patent proprietor] had a choice when drafting the application with respect to the claimed priority. However, this does not make the above adverse effect any more acceptable.

Other decisions

[1.4] Reference was made on behalf of the [opponents] to decisions T 1443/05, T 118/99, T 136/01 and T 494/03.

Decision T 1443/05 [4.1] concerned the addition of a disclaimer in the subsequent European application for which the priority was considered to be invalid. Although some examples did not contain the substance “CMIT”, the application as filed did not contain any indication from which the skilled person could directly and unambiguously derive the disadvantages of CMIT and the consequent exclusion of CMIT from the invention. The situation is therefore different from the present case.

In decision T 118/99 [3.2], the Board considered that it was implicitly stressed that the difference of one unit is technically relevant for the claimed process so that the residence times are technically different.

In decision T 136/01 [3.3], evidence was provided to the effect that the change in the lower end point of the temperature range has direct consequences on the polymers obtainable by the claimed treatment.

In decision T 494/03, the increased lower bound value was already explicitly disclosed in the priority document and there was no evidence that the difference is of significance. Therefore, the cases underlying these decisions differ from the present situation.

Conclusion

[1.5] The Board therefore considers that with the exception of the explicit reference to the particular SEC lower bound value of 0.330 kWh/kg, the subject-matter of claim 1 of the main request concerns the “same invention” as that disclosed in the priority document D0.

Entitlement to priority

[2.1] It is an undisputed fact that the value of 0.330 kWh/kg is not explicitly mentioned in the priority document D0. As the lower bound value of SEC of 0.330 kWh/kg cannot be directly and unambiguously derived from document D0, the subject-matter of claim 1 according to the main request - insofar as a method carried out at the lower bound value of 0.330 kWh/kg is concerned - is not entitled to the priority of document D0 (A 87(1)(b)).

As the priority document D0 was a European patent application that had been published as document D1, there is trouble in the air.

Novelty with respect to A 54(3) document D1

[2.2] Document D0 was filed 14 June 2001 and published as document D1 on 18 December 2002. The designated contracting states correspond to those of the patent in suit. In consequence, document D1 belongs to the state of the art under A 54(3) for all designated contracting states of the patent in suit.

In accordance with opinion G 3/93 of the EBA, a priority document which is published during the priority interval belongs to the state of the art for the later European application under A 54 insofar as the claim to priority is not valid. For the subject-matter of claim 1 of the main request, the claim to priority is not valid for a method carried out at the particular SEC lower bound value of 0.330 kWh/kg.

Claim 3 of document D1 refers back to claim 1 and thereby discloses a method of compounding a multimodal polyethylene composition in a compounding device, wherein

a) the total residence time of the polyethylene composition in the compounding device is at least 3 minutes,

b) the total drive specific energy (SEC) applied on the polyethylene composition is from 0.240 to 0.450 kWh/kg,

c) optionally, a specific cooling energy (SCC) of at most 0.200 kWh/kg is applied on the polyethylene composition,

d) the total specific energy, which is the difference between the total drive specific energy SEC and any specific cooling energy SCC, applied on the polyethylene composition is from 0.220 to 0.330 kWh/kg.

The subject-matter of claim 1 of the main request for a method carried out at a SEC value of 0.330 kWh/kg does not meet the requirements of a selection invention, because the value of 0.330 kWh/kg is close to the value of 0.325 kWh/kg disclosed in […] document D1.

Furthermore, as argued above in point [1.2], there is no proof that an SEC value of 0.330 kWh/kg gives rise to any identifiably other technical effect than that associated with the larger range disclosed in document D1. Therefore, at the SEC value of 0.330 kWh/kg, the subject-matter of claim 1 of the main request does not constitute a purposive selection giving rise to any new technical teaching.

In consequence, the subject-matter of claim 1 according to the main request is not novel with respect to document D1 under A 54(3).

In my opinion, as far as the “same invention” criterion is concerned, the present decision departs from the strict teaching of G 2/98, which is regrettable from the point of view of legal certainty. Nevertheless, the priority claim is invalidated because the “directly and unambiguously” criterion is found not to be satisfied. The Board thereby ignores that this criterion is at the very heart of the definition that G 2/98 has given of the “same invention”:

“The requirement for claiming priority of “the same invention”, referred to in A 87(1), means that priority of a previous application in respect of a claim in a European patent application in accordance with A 88 is to be acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole.

To sum up, the Board appears to have seen two criteria where in reality there is only one, but fortunately it has held that it was sufficient for the priority claim to be invalid that of them was not fulfilled. So the final outcome (loss of the priority claim) appears to be correct, but the way to get there is astonishing, to say the least.

Next time we shall see the even more surprising way in which the revocation of the patent was avoided.

If you wish to read the whole decision, you can download it here.