PATENT | The EPO BoA on non-reproducible products as prior art in inventive step

On 16 October 2025, the EPO Board of Appeal (the BoA) issued its decision in case T 1719/21 (Mitsui Chemicals, Inc. v Borealis GmbH), addressing among the others the issue whether a non-reproducible material could represent a suitable starting point in an inventive step analysis, in light of the Enlarged Board of Appeal’s (the EBA) ruling in G 1/23. 

Under G 1/23, a product made publicly available before a patent’s priority date is part of the state of the art, even if its composition or manufacturing method cannot be analysed or reproduced by the skilled person.

In T 1719/21, the BoA rejected the Patentee’s argument that such a non-analysable product cannot be considered a promising closest prior art purely because it could not be reproduced. The BoA held that, in the case at hand, such product constitutes a realistic starting point for the inventive step assessment, irrespective of whether the technical expert knows how to reproduce it.

Newsletter n. 114 – January 2026