EPO Board of Appeal: Clarity regarding a relative improvement of a known effect

If a claimed invention is defined by the use of a feature known per se to achieve a technical effect known per se, and the alleged technical contribution of the invention lies in a relative improvement of this effect, the clarity requirement under Art. 84 EPC generally demands that the feature defining this relative improvement be expressed in objectively verifiable terms. This is intended to ensure legal certainty for third parties regarding the scope of protection (EPO BoA 24.06.2025, T 2387/22, Sun Chemical/VMP pigments).