3.2.4 Common dependent claims 

While an independent claim is always part of the common matter among its dependent claims, the opposite is not true: a claim dependent on several independent claims is never part of the common matter between these independent claims.

Unity is assessed firstly between the independent claims. If a dependent claim comprises technical features common to several inventions, then it is part of all of these inventions at the same time.

Example 1

An application contains two independent claims and one dependent claim:

1. A device comprising feature A. 

2. A device comprising feature B. 

3. A device comprising features A and B. 

In this example, independent claims 1 and 2 are not linked by a single general inventive concept; features A and B are neither the same nor corresponding special technical features. A lack of unity is present between claims 1 and 2, each of them being directed to a different invention. The content of dependent claim 3 has no bearing on this analysis.

If dependent claims comprise features of two or more groups of inventions, then they belong to each of these group of inventions. In example 1, the subject-matter of claim 3 contains features of each of the two inventions (claim 1, claim 2), thus belonging to both inventions at the same time. Therefore, the search for the first invention mentioned in the claims should, in this example, cover the subject-matter of claim 1 and claim 3.

The examiner also assesses if a further search fee should be paid for the second invention (see F‑V, 2.2, F‑V, 3.4, B‑VII, B‑III, 3.8).

Example 2

An application comprises the following claims:

1. A device comprising feature A.  

2. A device according to claim 1, further comprising feature B. 

3. A device according to any of the previous claims, further comprising feature C.  

Claim 3 is thus directed to the following subject-matter:

3. A device that is either:  

(a)a device comprising features A and C; or  

(b)a device comprising features A, B and C.  

In this example, feature A is not a special technical feature (i.e. the subject-matter of claim 1 is either not new or not inventive).

– If both features B and C are special technical features (new and inventive) and they are corresponding (that is, they have a technical relationship with each other), then the claimed devices A+B and A+C are the same invention. Consequently, the device A+B+C is part of the same invention as well. There is unity of invention. 

– If features B and C are different and are not corresponding (that is, they have no technical relationship with each other), then there is a lack of unity. There are two inventions: the device having the features A+B (claim 1 partially and claim 2 entirely) and the device having the features A+C (claim 1 partially and claim 3(a) entirely). The subject-matter of claim 3(b) has all the features of the first invention (A+B) and all the features of the second invention (A+C). Therefore it belongs entirely to both inventions at the same time. Therefore the search for the first invention mentioned in the claims should, in this example, cover not only claim 2 (A+B), but also the subject-matter of claim 3(b) (A+B+C). 

The examiner also assesses if a further search fee should be paid for the second invention (see F‑V, 2.2, F‑V, 3.4, B‑VII, B‑III, 3.8).