a) Inventive step – furnishing of tests 

In T 570/08 the opponents had filed evidence in the form of comparative tests with the aim to support their argument that the claimed additive composition in the patent in suit did not solve the problem of improving lubricity and solubility of a diesel fuel oil. These results were in contrast to the tests which the patent proprietor had provided, so that the board was confronted with a series of tests leading to contradictory results. Therefore, the board could not share the patent proprietor's argument that the burden of proof rested with the opponents, since the opponents' test results cast doubts on the effect allegedly achieved by the present invention. The patent proprietor could not convincingly eliminate those doubts and the patent was revoked. By contrast, the board in T 1621/16 was satisfied that the technical report submitted with the appellant's grounds of appeal had shifted the burden of proof to the opponents, who then had to demonstrate that the technical problem in question had not been solved. Applying the balance of probabilities, the board concluded that it was technically plausible that the subject-matter of the claim solved the problem. After examining the obviousness, it held that the requirements of Art. 56 EPC were met.

In case T 2108/21, with detailed reference to T 862/11 and T 543/13 (see present chapter III.G.5.1.2c)), the board concluded that it was not immediately apparent for the person skilled in aerodynamics that the suction side winglet provided with the ranges of values for sweep and pre-bend defined in claim 1 would perform any better than the winglet of D1 disclosed with broader ranges of sweep and pre-bend. If any further or improved effect or advantage in terms of performance is alleged, then it should be supported by evidence in the patent. As both an explanation and data were missing any link between claimed parameter ranges and effect had not been plausibly demonstrated and thus the burden of proof shifted to the appellant proprietor. Under established case law, an unexpected effect of a patent has to be proven by comparative tests (T 1285/21; see also chapter I.D.4.3.2 and in this chapter III.G.5.1.2c)).