Under Art. 82 EPC, the European patent application must relate to one invention only or to a group of inventions so linked as to form a single general inventive concept. R. 44(1) EPC (cf. R. 30 EPC 1973) gives an interpretation of the concept of unity of invention where a group of inventions is claimed. The principles set out by board of appeal case law relating to the earlier version of R. 30 EPC 1973 in force until 31.5.1991 can still be applied.
For international applications the corresponding provisions on unity of invention are Art. 3(4)(iii) and in particular R. 13 PCT. Following the deletion of Art. 154(3) and 155(3) EPC 1973 as part of the revision of the EPC, protests in respect of additional fees paid to the EPO acting as ISA (Art. 17(3)(a), R. 40 PCT) or as IPEA (Art. 34(3)(a), R. 68 PCT) are no longer decided by the boards of appeal but by review panels of the EPO (see R. 158(3) EPC; for details of the current one-stage protest procedure before the EPO see Decision of the President of the EPO, OJ 2010, 320, and Notice from the EPO, OJ 2010, 322). The boards' competence to consider unity in the context of European applications remains unaffected. Given the harmonisation of the definitions concerning unity of invention in R. 13 PCT and Art. 82, R. 44 EPC, the criteria for unity in both systems are the same. Therefore, decisions of the boards of appeal rendered according to the former PCT protest procedures continue to be of interest for the consideration of unity in European applications.
The Guidelines for Examination in the EPO (version of June 2012) deal with unity of invention at the search stage in Part B-VII, unity as a procedural aspect of substantive examination in Part C-III, 3, and unity as a requirement of the European patent application in Part F-V. For international applications see Chapters 10 and 17 of the PCT International Search and Preliminary Examination Guidelines, as in force from 1.11.2011.