6. Plurality of inventions – further search fees
If the search division or the ISA raises an objection of lack of unity, a further search fee is payable under R. 64(1) EPC (R. 46(1) EPC 1973) or Art. 17(3)(a) PCT, respectively, for each additional invention to be covered by the second report (for Euro-PCT applications in the European phase, see in this chapter II.B.6.2.).
In W 2/10 the board pointed out that in W 4/85 (OJ 1987, 63) and many subsequent decisions, the boards had decided that the requirement to give reasons in an invitation under Art. 17(3)(a) PCT was so fundamental that an unsubstantiated invitation could be regarded as legally ineffective. This was so in the case in question and therefore the additional search fees had to be refunded. See also OJ 2017, A20 for the provisional opinion now issued together with the partial search report.
If the fee is paid in due time applicants may select the single invention or group of inventions which they wish to retain in the (main) application. According to T 158/12, with reference to G 2/92, this choice cannot be altered once examination of that invention has commenced. T 736/14 held that if an applicant responds unclearly or in a misleading way to an invitation from the examining division to specify which searched invention it wishes to prosecute further, then the division has to clarify this matter, e.g. via a further communication.