5. Procedure in the case of lack of unity during substantive examination
5.1 General principles
The final responsibility for establishing whether the application meets the requirement of unity of invention ultimately rests with the examining division (see T 631/97; see also C‑III, 3.2). For Euro-PCT applications which have entered the European phase, see F‑V, 7.
Whether or not the question of unity of invention has been raised by the search division, it must always be considered by the examining division. The conclusion reached may change, e.g. when further prior art becomes available at a later stage of the proceedings. When lack of unity of invention arises only during substantive examination, the examining division should raise an objection only in clear cases, particularly if substantive examination is at an advanced stage (see also H‑II, 6.3).
Whenever unity is found to be lacking, the applicants should be required to limit their claims in such a way as to overcome the objection (see C‑III, 3.2 and C‑III, 3.3), which means restricting them to a single searched invention (see H‑II, 6.1). Excision or amendment of parts of the description may also be necessary (see C‑III, 3.3). One or more divisional applications, covering matter removed to meet this objection, may be filed (see C‑IX, 1), provided that the parent application is pending (A‑IV, 1.1.1).