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The test for added subject matter

Addition and deletion of features

7.101 Addition or deletion of text, particularly when it relates to the features of the invention, can result in a specification including additional matter. Disclaimers are a similar amendment that can result in the addition of matter. Disclaimers are separately dealt with below. Care should be taken during examination whenever such changes are made, and similar considerations will apply in relation to divisional applications.

7.102 Deletion of a feature will often result in a broadening of the scope of a claim, but prior to acceptance the key consideration will be whether it results in a disclosure of added matter that was not in the specification as filed. In Protoned’s Application [1983] F.S.R. 110 the invention involved the use of a gas spring and a mechanical compression spring to adjust the seat and back of a chair. An amendment to change the definition of a “mechanical compression spring” to a “mechanical spring” was refused as it resulted in the application disclosing added matter inasmuch as it included the use of mechanical springs not referred to in the specification as filed.

7.103 An amendment which deletes or adds features may be allowable provided the invention is disclosed in the application when read as a whole. In particular, if the feature that has been deleted would be understood by the skilled person to be arbitrary or unnecessary then its deletion may be allowable. However, deletion of a feature from a claim will not be allowable if the original specification is construed as teaching that the feature is essential (see for example the “AMP/ Coaxial connector” decision T 0260/85).

7.104 Similarly, in Glatt’s Application [1983] RPC 122, the application as filed described an article for conditioning fabrics in a laundry dryer which comprised a flexible woven or non-woven air-permeable web. Amendment to omit the feature of air permeability was not allowed as this was considered to be an essential feature of the invention.

7.105 Raychem Ltd’s Application [1986] RPC 547, dealt with divisional applications in which a cross-linking step from the parent application was omitted from the claims of the divisional applications. This step was held by the Patent Court to be an essential feature of the invention described, and therefore claims to an intermediate product without the cross-linking step were considered to constitute additional matter. In the corresponding European applications, claims in which the intermediate was limited to containing cross-linkable groups, thereby incorporating the inventive concept, were found allowable.

7.106 In International Playtex Corporation’s Application [1969] RPC 362, the omission of a feature that was essential to fulfil the purpose of the invention was not allowable. In particular, the specification as filed stated that the object of the invention was to design a brassiere with maximum resistance to riding over derived from its built-in differential stretch patterns. The applicant sought to replace this text with one referring to “a triangular insert” based on a feature defined in the claims (“a triangular piece of stretchable fabric”), but the Court considered that this was not an allowable amendment.

7.107 There may also be situations where an invention is claimed in a different manner but is still the same inventive concept. In Southco Inc. v Dzus Fastener Europe Ltd [1990] RPC 587 at [616], Aldous J:

“There is no definition in the Act of what is meant by the word ‘matter’ and I believe that this word is wide enough to cover both structural features of the mechanism and inventive concepts … What the Act is seeking to prevent is a patentee altering his claims in such a way that they claim a different invention from that which is disclosed in the application. Thus, provided the invention in the amended claim is disclosed in the application when read as a whole, it will not offend against section 76 …”

7.108 If a claim does not define a particular feature, it does not necessarily follow that this feature must be absent. As a consequence, amendment of a claim to specifically define the absence of a feature could in fact lead to additional matter (T 170/87 “SULZER/ Hot gas cooler”).