4. Cascading non-unity 

If an international application is found to lack unity at the search stage, the invention first mentioned in the claims will be searched and the applicant is invited to pay additional search fees for the other invention(s) (see B‑VII, 2).

If additional search fees are paid in response to an invitation to do so and the additional search(es) reveal(s) a further lack of unity "a posteriori", no further invitation to pay further additional search fees is issued.

If the applicant pays additional search fees for any of the other inventions, a search is carried out for those inventions.

If this further search reveals that one or more of these inventions also lack unity "a posteriori", only the first invention in each group of inventions is searched. The applicant will not be invited to pay another set of search fees at this stage of the proceedings.

An "a priori" non-unity objection cannot be raised at this stage, and the "a posteriori" non-unity objection should not be raised in borderline cases.

If the applicant pays (an) additional search fee(s), a search is carried out for the invention(s) for which the search fee(s) has/have been paid.

If the search reveals that one or more of these inventions also lack unity "a posteriori", only the first invention of each of the groups of inventions is searched.

The WO‑ISA will be drafted for all the searched inventions. Section III must be modified to cover the inventions actually searched. Under Section IV, full reasons must be given for all the non-unity objections raised. Under Section V an opinion as to novelty, inventive step and industrial applicability must be given for all searched inventions.

Claims not searched during the international phase can be prosecuted during the regional phase before the EPO in accordance with EPC Guidelines F‑V, 7.1, as appropriate.

Example

A lack of unity objection is raised by the EPO acting as ISA, identifying four different inventions A, B, C and D. The first invention A is searched and the applicant is invited to pay further search fees for inventions B, C and D.

The applicant pays two further search fees for inventions B and C. During the additional search, B is found to lack unity "a posteriori" and is divided into the groups of inventions B1, B2 and B3.

In this case only B1 and C are searched, so in Section III of the WO‑ISA the claims relating to inventions B2, B3 and D are indicated as not searched. In Section IV, full reasons must be given for why the claims of the application were divided into A, B, C and D and why B was further subdivided into B1, B2 and B3. Under Section V an opinion on patentability must be given for A, B1 and C.

Examination of the application in the European phase will be based on either A, B1 or C (see EPC Guidelines F‑V, 7.1(iii)). For the claims relating to inventions B2, B3 and D, an invitation under Rule 164(2) EPC will be issued in accordance with EPC Guidelines F‑V, 7.1(iv).