In T 843/91 of 17 March 1993 date: 1993-03-17 the board noted that disqualifying partiality presumed a preconceived attitude on the part of a deciding person towards a party (see also T 1028/96 of 15 September 1999 date: 1999-09-15). More precisely, in the board's view, partiality would be willingly to favour one party by granting it rights to which it was not entitled, or by intentionally disregarding the rights of the other party (see also T 261/88 of 16 February 1993 date: 1993-02-16). The question whether an objection to board members on the ground of suspected partiality was justified could only be decided in the light of the particular circumstances of each individual case (see also G 5/91). The board found that, whatever their gravity, deficiencies, erroneous practices or procedural violations could not be regarded as a basis for an objection on the ground of partiality if they did not result from such a preconceived attitude or deliberate intention (see also T 1257/14 of 5 February 2018 date: 2018-02-05).

In the appeal proceedings underlying R 17/09 members of the board used the term "man in the street". The Enlarged Board found that in English this term had no pejorative associations but was commonly used to describe an average citizen. It could see no support for the allegation that members of the board were influenced in their decision by any bias against the petitioner.