PA 09/2008: The consequences of a finding of lack of unity of invention of an international application on (i) the international preliminary examination and (ii) the national phase

WARNING: Although the information which follows was correct at the time of original publication in the PCT Newsletter, some information may no longer be applicable; for example, amendments may have been made to the PCT Regulations and Administrative Instructions, as well as to PCT Forms, since the PCT Newsletter concerned was published; changes to certain fees and references to certain publications may no longer be valid. Wherever there is a reference to a PCT Rule, please check carefully whether the Rule in force at the date of publication of the advice has since been amended.

Q:  The International Searching Authority (ISA), when searching an international application filed by my company, found that it did not fulfill the requirements of unity of invention and invited me to pay several additional search fees. Although we wanted, nevertheless, to proceed with the international application, we were not in a position to pay the extra fees, a consequence of which is that certain parts of the application were not searched. What will be the consequences of such a partial search if we file a demand for international application in respect of the application, and what will be the consequences for the national phase?

A:  As was explained in the “Practical advice” in PCT Newsletter No. 08/2008, the international application must relate to one invention only or to a group of inventions so linked as to form a single general inventive concept (PCT Rule 13). For further information on the finding of lack of unity by the ISA, please refer to that item.

Lack of unity of invention where a demand is filed

If you file a demand for international preliminary examination, the International Preliminary Examining Authority (IPEA) will check the claims for unity of invention, even where some or all additional search fees have been paid and the international search report (ISR) has been established on more than just the main invention.

However, the IPEA need not, and generally will not, examine any claims relating to unsearched inventions (see PCT Rule 66.1(e)), even where you have requested the IPEA to base the examination on any amendments under PCT Articles 19 and/or 34.

If the IPEA considers that the international application does not comply with the unity of invention requirements, it may, using Form PCT/IPEA/405, inform you why there is a lack of unity of invention and, in accordance with PCT Rule 68.2, invite you within one month from the invitation either to:

a)      restrict the claims to those which have been searched and which meet the requirements of unity of invention (in which case the IPEA must specify at least one possibility of restriction), or

b)      pay additional preliminary examination fees.

Any additional preliminary examination fee may, in accordance with PCT Rule 68.3(c), be paid under protest, in which case procedures similar to those explained in relation to the international search apply – see the “Practical advice” in PCT Newsletter No. 08/2008. The examination of such a protest may be subjected by the IPEA to the payment to it of a protest fee (PCT Rule 68.3(e)) (for details, consult the PCT Applicant’s Guide, Annex E, for the IPEA concerned). If you neither restrict the claims nor pay additional fees, the examination will be carried out on the main invention only, unless you request otherwise.

Alternatively, there are cases of lack of unity of invention where, compared with the procedure of inviting the applicant to restrict claims or to pay additional fees, no or little additional effort is involved in establishing the international preliminary examination report (IPER) for the entire international application. Then, for reasons of economy, the examiner may avail himself/herself of the option referred to in PCT Rule 68.1 by choosing not to invite the applicant to restrict the claims or to pay additional fees, but rather, to carry out the international preliminary examination on the entire international application and express his/her views on the lack of unity of invention in the IPER, specifying the reasons therefor.

For further information on the procedure before the IPEA where unity of invention is lacking, see the PCT International Search and Preliminary Examination Guidelines at:

as well as the PCT Applicant’s Guide, International Phase, paragraphs 398 and 399 at:

Possible negative consequences in the national phase

The fact that not all claims were searched by the ISA does not, in itself, have any influence on the validity of the international application, the processing of which, including its communication to the designated (or elected) Offices, continues in respect of all claims. Nevertheless, the national law of any State may provide that such unsearched and/or unexamined parts of the international application will be considered withdrawn as far as that State is concerned unless a special fee is paid by the applicant to its national Office (PCT Articles 17(3)(b) and 34(3)(c)) – note, however, that there are only a few States which directly apply such provisions (for example, China and Sweden) though others may charge further fees for the establishment of searches before any patent can be granted. Similar fees may apply in accordance with PCT Article 34(3)(b) if the applicant chooses to restrict the claims during international preliminary examination but then wishes to pursue the claims during the national phase which were not the subject of international preliminary examination.

In the national phase, it is possible that designated Offices may review the conclusions of the International Searching and Preliminary Examining Authorities and come to different conclusions regarding unity of invention. These Offices may also require additional inventions to be removed from the application or to be continued in a divisional application if necessary. However, in accordance with PCT Articles 27(1) and 27(4), the Offices must form their views based on the criteria set out in PCT Rule 13, unless the result of alternative national criteria is more favorable to the applicant (meaning that fewer fees, amendments and divisional applications would be required).


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