The determination of lack of unity of invention may arise from two situations. In one situation lack of unity may be directly evident “a priori,” that is, before considering the claims in relation to any prior art. Alternatively, lack of unity may only become apparent “a posteriori,” that is, after taking (at least some) prior art into consideration. [PCT/GL/ISPE/12 at para 10.03].

The determination of a priori lack of unity is independent of any knowledge of the relevant prior art. Thus, respective inventions claimed need to be assessed to determine whether they each involve one or more of the same or corresponding special technical features. If they include one or a group of such features, then prima facie the inventions will possess unity a priori.

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, there is 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.

The first example given at Annex E illustrates an a priori lack of unity situation. So too does para 10.03 of the PCT International Search and Preliminary Examination Guidelines.

Where, as in the example above, two inventions under consideration are of the form A + X and A + Y, in considering lack of unity a priori, either the description in the specification or the manner of claiming (such as a two-part claim) may indicate that the common feature A does not on its own make any technical contribution to the inventions. For example, if A represents a feature that the specification indicates as being prior art or known, or would otherwise be understood by a skilled person to be well known in the art, then it would not possess the characteristic of a "special technical feature" per PCT Rule 13.2.

As an illustrative example of the last alternative in the previous paragraph, the feature A may represent a single feature (such as 'an adjustable chair') or a group of features (such as 'an adjustable chair having a movable back rest'). In considering lack of unity a priori, either form of feature A would (today) be recognised as well known, or at least be seen as generic in the art, and thus not on its own qualify as a special technical feature. Thus, in lack of unity, a priori could be taken in this situation with reasons given for considering the feature as well known or generic. If there is any reasonable doubt that feature A is known or generic, then material showing that it is should be identified and lack of unity a posteriori taken based on that material. (See EPO decision case W0038/90 for an example).

The above example assumes that features X and Y are not closely technically related whereby the respective inventions do not otherwise embody the same general inventive concept.

A determination of lack of unity, a posteriori can arise where relevant independent claims have features in common, but those features appear not to be novel given the prior art, thus leaving the claims without a single general inventive concept. [PCT/GL/ISPE/12 at para 10.08]

A determination of lack of unity a posteriori can also arise with dependent claims in an application where the prior art shows a presumption of lack of novelty or inventive step in an independent claim to which they relate. This can follow from the finding for the independent claim if there is no technical relationship left over the prior art among the claimed inventions involving one or more of the same or corresponding special technical features, thus leaving two or more dependent claims without a single general inventive concept. [See example 40 in paragraph 10.59A of PCT/GL/ISPE/12].

In order to raise an objection of lack of unity a posteriori the examiner needs to prove that the common feature(s) or claim is not novel or does not clearly involve an inventive step; for example, by citing relevant patent specifications, journals or textbooks. The invitation to pay additional fees needs to clearly indicate the basis for concluding why the common feature lacks novelty or an inventive step.

The second example given at Annex E illustrates an a posteriori lack of unity situation as do paras 10.08 and 10.59 to 10.59A of the PCT International Search and Preliminary Examination Guidelines.

In considering the prior art for lack of unity a posteriori, no account should be taken of subject matter disclosed in any E or P category documents.

Example 41 to 42 in paragraphs 10.59B and 10.59C of the PCT International Search and Preliminary Examination Guidelines discuss how a lack of unity of invention can arise within a single independent claim, and example 43 in paragraph 10.59D explains the consideration required to determine unity of invention in complex claim sets where claims contain features that overlap with the features of other claims.

Amended Reasons

Amended Reason	Date Amended
	18 Oct 2023
Published for testing	06 Jun 2023