T 1457/13 - Proof technical effect in opposition

Key points

• This opposition appeal decision is interesting, in that the Boards considers the technical effect of one of the distinguishing features (of claim 1 as granted) to be not proven, because the comparative experiments differ by more than the distinguishing feature of the claim. 
• Accordingly, the Board implicitly gave the patent proprietor rather than the opponent the burden of proof of showing that the invoked technical effect was indeed provided by the distinguishing feature of claim 1 as granted (the patent as granted did not demonstrate this).

EPO T 1457/13 -  link

1.2 Technical problem

1.2.1 Claim 1 of the main request requires that the amount of vinyl group on the polyethylene be at least 0.2 vinyl groups /1000 carbon atoms. According to paragraph 19 of the description, the vinyl groups are usually attributed to a polymer termination reaction after an ethylene insertion. It is concluded from that passage that the presence of vinyl groups on the polyethylene results from a common reaction in the course of polymerization and that it is not specific to the polymerization process used in the patent in suit. Also, the description does not provide any further teaching relating to the effect that feature might have on the properties of the polyethylene produced. The amount in vinyl groups on the polyethylenes produced in example 1 (1.3 vinyl groups /1000 carbon atoms) and comparative example 1 (0.12 vinyl groups /1000 carbon atoms) are reported in Table 1. The polyethylene compositions of these two examples are however different polymeric compositions altogether since the polyethylene composition of example 1 is produced from ethylene and 1-hexene and that of comparative example 1 is produced from ethylene and 1-butene. It is therefore not possible to establish with certainty whether any improvement in the properties of the composition of example 1, which is according to claim 1 of the main request, results from the specific amount of vinyl groups of the polyethylene or from the different monomer used in the preparation of the polyethylene composition. According to the established case law of the Boards of Appeal, for a comparative test to demonstrate an inventive step with an improved effect over a claimed area, the nature of the comparison with the closest state of the art must be such that the effect is convincingly shown to have its origin in the distinguishing feature of the invention. For this purpose it may be necessary to modify the elements of comparison so that they differ only by such a distinguishing feature (see T 197/86, point 6.1.3, OJ EPO, 1989, 371). Since the patent in suit did not offer a fair comparison and since the appellant did not provide it either, no effect can be attributed to the choice of an amount in vinyl groups on the polyethylene of at least 0.2 vinyl groups /1000 carbon atoms.