PCT International Search and Preliminary Examination Guidelines


Chapter 10  Unity of Invention

Determination of Unity of Invention

Article 17(3)(a); Rule 13; Section 206

10.01  An international application should relate to only one invention or, if there is more than one invention, the inclusion of those inventions in one international application is only permitted if all inventions are so linked as to form a single general inventive concept (Rule 13.1). With respect to a group of inventions claimed in an international application, unity of invention exists only when there is a technical relationship among the claimed inventions involving one or more of the same or corresponding special technical features. The expression “special technical features” is defined in Rule 13.2 as meaning those technical features that define a contribution which each of the inventions, considered as a whole, makes over the prior art. The determination is made on the contents of the claims as interpreted in light of the description and drawings (if any).

Rule 13.2; AI Annex B, paragraph (b)

10.02  Whether or not any particular technical feature makes a “contribution” over the prior art, and therefore constitutes a “special technical feature,” is considered with respect to novelty and inventive step. For example, a document discovered in the international search shows that there is a presumption of lack of novelty or inventive step in a main claim, so that there may be no technical relationship left over the prior art among the claimed inventions involving one or more of the same or corresponding special technical features, leaving two or more dependent claims without a single general inventive concept.

Rule 13.2

10.03  Lack of unity of invention may be directly evident “a priori,” that is, before considering the claims in relation to any prior art, or may only become apparent “a posteriori,” that is, after taking the prior art into consideration. For example, independent claims to A + X, A + Y, X + Y can be said to lack unity a priori as there is no subject matter common to all claims. In the case of independent claims to A + X and A + Y, unity of invention is present a priori as A is common to both claims. However, if it can be established that A is known or obvious (see Chapter 13 for guidance on obviousness), there may be lack of unity a posteriori, since A (be it a single feature or a group of features) is not a technical feature that defines a contribution over the prior art.

10.04  Although lack of unity of invention should certainly be raised in clear cases, it should neither be raised nor persisted in on the basis of a narrow, literal or academic approach. There should be a broad, practical consideration of the degree of interdependence of the alternatives presented, in relation to the state of the art as revealed by the international search or, in accordance with Article 33(6), by any additional document considered to be relevant. If the common matter of the independent claims is well known and the remaining subject matter of each claim differs from that of the others without there being any unifying novel inventive concept common to all, then clearly there is lack of unity of invention. If, on the other hand, there is a single general inventive concept that appears novel and involves inventive step, then objection of lack of unity does not arise. For determining the action to be taken by the examiner between these two extremes, rigid rules cannot be given and each case is considered on its merits, the benefit of any doubt being given to the applicant.

10.04A  In order to assess whether an application claims non-unitary subject-matter, the Authority may apply the “minimum reasoning” methodology by ascertaining the common or corresponding matter, if any, between the (groups of) inventions, why this matter cannot provide a single general inventive concept because of the lack of the same or corresponding special technical features, and why there is no technical relationship among the (groups of) inventions, if not apparent.  In particular, the analysis of whether there is a technical relationship among the (groups of) inventions may encompass an indication of the non‑common technical features and why claims may be grouped together, a statement of why these features are different, the identification of the technical properties for each group demonstrated through their features and an explanation why their technical properties are different, if not apparent.  Where appropriate, depending on the technical field, e.g. chemistry, the analysis of the technical properties demonstrated through their features can instead explain that a grouping of alternatives of compounds are not of a similar nature, that the intermediate and final products do not have the same essential structural element and are not technically closely interrelated, that a process is not specially adapted to the production of a product, that a product itself does not provide a single general inventive concept linking different uses, or that a use in itself does not provide a single general inventive concept linking the claims.  Examples of use of minimum reasoning are provided in paragraphs 10.59E to 10.59J.

10.05  From the preceding paragraphs it is clear that the decision with respect to unity of invention rests with the International Searching Authority or the International Preliminary Examining Authority. However, the Authority should not raise objection of lack of unity of invention merely because the inventions claimed are classified in separate classification groups or merely for the purpose of restricting the international search to certain classification groups.

AI Annex B, paragraph (c)

10.06  Unity of invention has to be considered in the first place only in relation to the independent claims in an international application and not the dependent claims. By “dependent” claim is meant a claim which contains all the features of one or more other claims and contains a reference, preferably at the beginning, to the other claim or claims and then states the additional features claimed (Rule 6.4). The examiner should bear in mind that a claim may also contain a reference to another claim even if it is not a dependent claim as defined in Rule 6.4. One example of this is a claim referring to a claim of a different category (for example, “Apparatus for carrying out the process of Claim 1 ...,” or “Process for the manufacture of the product of Claim 1 ...”). Similarly, in a situation like the plug and socket example in paragraph 5.19, a claim to the one part referring to the other cooperating part, for example, “plug for cooperation with the socket of Claim 1 ...”) is not a dependent claim.

10.07  If the independent claims avoid the prior art and satisfy the requirement of unity of invention, no problem of lack of unity arises in respect of any claims that depend on the independent claims. In particular, it does not matter if a dependent claim itself contains a further invention. For example, suppose claim 1 claims a turbine rotor blade shaped in a specified manner, while claim 2 is for a “turbine rotor blade as claimed in claim 1” and produced from alloy Z. Then no objection under Rule 13 arises either because alloy Z was new and its composition was not obvious and thus the alloy itself already contains the essential features of an independent possibly later patentable invention, or because, although alloy Z was not new, its application in respect of turbine rotor blades was not obvious, and thus represents an independent invention in conjunction with turbine rotor blades. As another example, suppose that the main claim defines a process for the preparation of a product A starting from a product B and the second claim reads: “Process according to claim 1 characterized by producing B by a reaction using the product C.” In this case, too, no objection arises under Rule 13.1, whether or not the process for preparation of B from C is novel and inventive, since claim 2 contains all the features of claim 1. The subject matter of claim 2 therefore falls within claim 1. Equally, no problem arises in the case of a genus/ species situation where the genus claim avoids the prior art and satisfies the requirement of unity of invention. Moreover, no problem arises in the case of a combination/subcombination situation where the subcombination claim avoids the prior art and satisfies the requirement of unity of invention and the combination claim includes all the features of the subcombination.

10.08  If, however, an independent claim does not avoid the prior art, then the question whether there is still an inventive link between all the claims dependent on that claim needs to be carefully considered. If there is no link remaining, an objection of lack of unity a posteriori (that is, arising only after assessment of the prior art) may be raised. Similar considerations apply in the case of a genus/species or combination/subcombination situation. This method for determining whether unity of invention exists is intended to be applied even before the commencement of the international search. Where a search of the prior art is made, an initial determination of unity of invention, based on the assumption that the claims avoid the prior art, may be reconsidered on the basis of the results of the search of the prior art.

10.09 Alternative forms of an invention may be claimed either in a plurality of independent claims, or in a single claim (but see paragraph 5.18). In the latter case, the presence of the independent alternatives may not be immediately apparent. In either case, however, the same criteria are applied in deciding whether or not there is unity of invention, and lack of unity of invention may then also exist within a single claim. Where the claim contains distinct embodiments that are not linked by a single general inventive concept, the objection as to lack of unity of invention is raised. Rule 13.3 does not prevent an Authority from objecting to alternatives being contained within a single claim on the basis of considerations such as clarity, the conciseness of claims or the claims fee system applicable in that Authority.

10.10 Objection of lack of unity of invention does not normally arise if the combination of a number of individual elements is claimed in a single claim (as opposed to distinct embodiments as discussed in the paragraph immediately above), even if these elements seem unrelated when considered individually (see paragraph 15.31).