Determining Lack of Unity

Date Published

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. [Rule 13.1]

The basic test to be applied in determining whether or not there is unity of invention is set out in PCT Rules 13.2 to 13.3.  In applying these rules, the guidelines and examples in Chapter 10 of the PCT International Search and Preliminary Examination Guidelines are to be followed.

Unity of invention is present between a group of claimed inventions only when there is a technical relationship among those inventions involving one, or more of the same or corresponding special technical features.  The expression "special technical features" means those technical features that define a contribution which each of the claimed inventions, considered as a whole, makes over the prior art. [Rule13.2]

The determination of unity of invention is made on the contents of the claims as interpreted in light of the description and drawings (if any).

Examples 5 and 22 in paragraphs 10.25 and 10.42 of the PCT International Search and Preliminary Examination Guidelines, respectively, illustrate some instances of corresponding special technical features. 

A useful starting point to assess unity of invention is to consider what the problem is that the application addresses.  This leads on to what is the way that the application solves that problem.  The general solution is probably the general inventive concept.  If that concept is reflected by the technical features in all the claims then, prima facie, unity of invention may exist.  If the technical features also define a contribution which each claimed invention makes over the prior art, then they are the "special technical features" in the terms of Rule13.2 and unity of invention is present.  Note that the general concept can be evident indirectly, i.e. the form of the invention claimed takes advantage of, or relies on, the general concept.

The determination of unity of invention is made regardless of whether the inventions are claimed in separate claims or as alternatives within a single claim. [Rule 13.3]

Where a claim contains distinct embodiments which are not linked by a single general inventive concept, the objection as to lack of unity of invention should be raised. [PCT/GL/ISPE/10 at para 10.09 and example 42 in para 10.59C]

Unity is considered in the first instance, only in relation to the independent claims. If the independent claims satisfy the requirements of unity of invention and overcome the prior art then no unity problem will arise in relation to any of the dependent claims. Where an independent claim does not overcome the prior art then the inventive link between all the dependent claims must be considered carefully. There is often a residual a posteriori lack of unity in dependent claims arising from a novelty objection. Where there are different significant embodiments in the dependent claims, an objection of lack of unity a posteriori (that is, arising only after assessment of the prior art) may be applicable. [PCT/GL/ISPE/10 at para 10.08]

Where the special technical feature is known, then that feature cannot make a contribution over the art.  It is then necessary to attempt to reformulate the problem and reassess the special technical feature.  If the special technical feature clearly lacks an inventive step compared to the prior art, then the same conclusion follows.

Lack of unity of invention should be based on sound reasons and be raised in clear cases.  Care should be exercised in not raising it based on a narrow, literal or academic approach. [PCT/GL/ISPE/10 at para 10.04]