In contrast to the current rule, R. 164(1) EPC in its previous version(s) prescribed that a European supplementary search report was to be drawn up on the invention or group of inventions first mentioned in the claims. Where no such supplementary search was to be carried out (i.e. where the EPO drew up the international search report or a supplementary international search report), the applicant had no possibility in the European phase to pay further search fees in that application in respect of inventions not covered by the international search report or any supplementary international search report. R. 164(2) EPC required the examining division, where it found that the application documents did not meet the unity requirements, or protection was sought for an invention not covered by the international search report, supplementary international search report or supplementary European search report, to invite the applicant to limit the application to one searched invention. Unsearched inventions could only be pursued in European divisional applications.

The following board of appeal decisions concern former R. 164 EPC.

In J 3/09, the Legal Board of Appeal confirmed in respect of R. 164 EPC (as then in force) that although the procedure on entry of an application into the European phase where the EPO had acted as the ISA changed with the coming into force of EPC 2000, the responsibility for establishing whether or not the application met the requirements of unity of invention still ultimately rested with the examining division, and the opinion of the EPO acting as the ISA on lack of unity was not final or binding on the examining division. The board observed that the practice of the examining division in this respect remained as before, noting in particular that to the extent that an objection of non-unity raised by the ISA turned out to be unjustified, the applicant was entitled to have the whole subject-matter of his unitary invention searched. This was also apparent from the then wording of R. 164(2) EPC, giving the EPO the power to invite the applicant to limit the application to one invention. This implied that where there was in fact only "one" invention there was no sanction.

The board in T 1285/11 followed this reasoning, adding that the fact that the applicant did not pay further search fees or protest fees in the international phase could not be seen as a tacit agreement with the findings of non-unity of the ISA. As to the wording of R. 164(2) EPC as then in force, it could be deduced from the juxtaposition of "an invention not covered by the international search report" and "one invention covered by the international search report" that, for the Rule to be applicable, the non-searched and searched inventions must indeed be non-unitary with respect to one another. In the case in hand, there was, prima facie, a feature which could be regarded as a special technical feature establishing unity between "invention 1" and "invention 2", and R. 164(2) EPC as then applicable could not be seen as a bar to further prosecution based on the main request.

In considering the applicability of R. 164(2), second half-sentence, EPC in the version then in force, the board in T 507/11 referred to the sanction of G 2/92 (OJ 1993, 591), whereby the application may not be pursued for subject-matter in respect of which no search fee has been paid. In the board’s view, this sanction did not necessarily apply to features disclosed in the original application documents in connection with an invention or group of inventions which has been searched. In the case in point, amended claim 1 contained all the features of searched claims 1 and 2. Protection was therefore still sought for the first, searched invention, now further restricted by features of original claim 13 (attributed by the ISA to another invention and therefore not searched), which, on account of the dependencies in the original claims, had been clearly and unambiguously disclosed. There was therefore no change to an unsearched invention. See also T 442/11 and T 509/11.

Further decisions concerned with the interpretation and application of former R. 164 EPC are T 1981/12, T 2473/12, T 2459/12 and T 145/13 (see also the section that follows).