Article 21²⁰, ²¹
Boards of Appeal

(1) The Boards of Appeal shall be responsible for the examination of appeals from decisions of the Receiving Section, the Examining Divisions and Opposition Divisions, and the Legal Division. 

(2) For appeals from decisions of the Receiving Section or the Legal Division, a Board of Appeal shall consist of three legally qualified members. 

(3) For appeals from a decision of an Examining Division, a Board of Appeal shall consist of: 

(a) two technically qualified members and one legally qualified member, when the decision concerns the refusal of a European patent application or the grant, limitation or revocation of a European patent, and was taken by an Examining Division consisting of less than four members; 

(b) three technically and two legally qualified members, when the decision was taken by an Examining Division consisting of four members, or when the Board of Appeal considers that the nature of the appeal so requires; 

(c) three legally qualified members in all other cases. 

(4) For appeals from a decision of an Opposition Division, a Board of Appeal shall consist of: 

(a) two technically qualified members and one legally qualified member, when the decision was taken by an Opposition Division consisting of three members; 

(b) three technically and two legally qualified members, when the decision was taken by an Opposition Division consisting of four members, or when the Board of Appeal considers that the nature of the appeal so requires.