In G 1/05 (OJ 2007, 362), the Enlarged Board of Appeal stated that the principle of equal treatment and the right of parties to a fair trial enshrined in Art. 6(1) of the Convention for the Protection of Human Rights and Fundamental Freedoms (ECHR) oblige the boards of appeal to decide the individual cases pending before them according to uniformly applied criteria and not in an arbitrary manner. The establishment of a uniform jurisprudence which is consistently applied to the individual cases under consideration appears, thus, as a means to safeguard that justice is done to the parties, on condition that the principles developed in the jurisprudence are applied to the individual cases under consideration in a manner which takes due account of their particulars, if any.
According to the Enlarged Board, the right to object to a judge for reasons of suspicion of partiality is meant to prevent that a judge is influenced in his or her decision-making - be it deliberately or inadvertently - by extraneous considerations, prejudices and predilections, i.e. by considerations other than the arguments he or she considers factually and legally relevant for the case under consideration. A suspicion of partiality might arise where there are circumstances possibly justifying a suspicion of a tendency to favour one or more of the parties or to discriminate against one of them. However, any such suspicion must be based on the specific facts of the case. These principles appear to be commonly accepted in the laws of the contracting states and the jurisprudence of the boards of appeal. These considerations must apply to the proceedings before the Enlarged Board of Appeal in the same manner as they apply to the proceedings before the boards of appeal.
The Enlarged Board of Appeal further stated that it is very important that board members discharge their duty to sit in the cases allocated to them. That duty, viz. the right of the parties to a hearing before a judge or court in the particular composition as determined by the provisions applicable thereto ranks at constitutional level in some of the contracting states and is also recognised in the jurisprudence of the boards of appeal (see T 954/98, point 2.2 of the Reasons; J 15/04, point 12 of the Reasons; R 15/11, point 10 of the Reasons).
The Enlarged Board of Appeal pointed out in interlocutory decision G 2/08 of 15 June 2009 that the boards of appeal and the Enlarged Board, respectively, act as judicial bodies and apply general principles of procedural law. Duly appointed by law, members of the Enlarged Board of Appeal have the duty to sit on the cases allocated to them according to their jurisdiction both "ratione legis" and "ratione materiae". That is, parties to judicial proceedings have a right to have their case considered and decided by the judge designated or appointed by law (Droit d'être jugé par son juge naturel; Recht auf den gesetzlichen Richter). This essential principle is even enshrined at constitutional level in some EPC contracting states, e.g. Germany, Austria, and Switzerland. Once established by law the judge is deemed to act in good faith and is therefore presumed impartial until proven otherwise (cf. ECHR: De Cubber v. Belgium, 26 October 1984; ETTL v. Austria, 23 April 1987; Hauschildt v. Denmark, 24 May 1989; Academy Trading Ltd et al. v. Greece, 4 April 2000). On the other hand Art. 6(1) ECHR, relying on principles of law common to the member states of the European Patent Organisation and applying to all departments of the said organisation, requires inter alia that "in the determination of his civil rights and obligations ... everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal established by law". These principles are not incompatible and have to be construed in such a way that they are not mutually exclusive.
The Enlarged Board of Appeal went on to state that it is the duty of board members not to sit in proceedings in which their impartiality could be reasonably doubted, whatever their feelings might be.
In decisions G 5/91 and G 1/05 the Enlarged Board of Appeal underlined the importance of a very strict observance of the requirement of impartiality in proceedings before the boards of appeal and the Enlarged Board of Appeal in view of their judicial functions at final instance within the European patent granting system. Hence, the Enlarged Board stated that it is a general principle of law that a member should not decide a case in which one might have good reason to assume or even suspect partiality.