10.2. Technical prejudice

According to the case law of the boards of appeal (see T 119/82, OJ 1984, 217; T 48/86), inventiveness can sometimes be established by demonstrating that a known prejudice, i.e. a widely held but incorrect opinion of a technical fact, needs to be overcome. In such cases, the burden is on the patentee (or patent applicant) to demonstrate, for example by reference to suitable technical literature, that the alleged prejudice really existed (T 60/82, T 631/89, T 695/90, T 1212/01, T 1989/08, T 3016/18).

A prejudice in any particular field relates to an opinion or preconceived idea widely or universally held by experts in that field. The existence of such prejudice is normally demonstrated by reference to the literature or to encyclopaedias published before the priority date. The prejudice must have existed at the priority date, any prejudice which might have developed later is of no concern in the assessment of inventive step (T 341/94; see also T 531/95, T 452/96, T 1212/01, T 25/09, T 99/19, T 1328/20).

In T 3016/18 the board confirmed that the existence of a technical prejudice could, in case of doubt, be an auxiliary consideration in assessing whether there was inventive step, but was no substitute for a technical expert assessment of the invention vis-à-vis the state of the art.