IP and IT Law Bytes: Patents: Added Matter

03 March 2014


The Court of Appeal has held that a patent for disc brake calipers for motor vehicles was not invalid for added matter.


A patent may be revoked if the matter disclosed in the specification extends beyond that disclosed in the application as filed (section 72(1)(d), Patents Act 1977) (1977 Act). So, if a patent is amended to include subject matter that extends beyond the application, and the added matter cannot be removed, the patent will be invalid.

Following Bonzel v Intervention (No 3), whether there is “added matter” is determined by comparing what, from the view of the skilled addressee, is disclosed explicitly and implicitly in the application and in the specification ([1991] RPC 553). Subject matter will be added unless such matter is clearly and unambiguously disclosed in the application (explicitly or implicitly).


AP owned a patent for disc brake callipers for motor vehicles. AP brought an action against AL in the former Patents County Court for patent infringement. The Patents County Court held that AP’s patent was invalid for added matter. If the patent was valid, four out of the five products sold by AL would infringe. AP appealed.


The court upheld AP’s appeal. The court applied the Bonzel test and found that there was no material difference between the technical disclosure from the application and that in the granted patent. The patent claimed a wider class of all asymmetric versions of a specific feature, rather than the specific embodiment disclosed in the application. However, the description in the application was of a shape which was “necessarily asymmetrical”. The description of asymmetric in the claims had to be read as part of the disclosure of the granted patent as a whole, taking account of the different functions of the specification on the one hand and the claims (which delimit the monopoly of the patent) on the other.

The court held that, although disclosing new information about the invention is not allowed, the law does not prohibit adding claim features that state in more general terms that which is described in the specification.

The skilled person would understand that the specification read as a whole did not disclose any configuration not already disclosed in the application. He would understand that the patentee had drafted his claims to cover asymmetric features generally and that such features in the granted patent were simply exemplified by the more specific shape described in the embodiments in the application. He would not, therefore, learn any new information about the invention.


Decisions on added matter focus on the relationship between the scope of the granted claims and what is disclosed in both the specification of the granted patent and the corresponding application. The key finding here was that the skilled person would understand that the claim was supported by a correspondingly broad disclosure in the application, and that it may be legitimate to add claim features that state in more general terms what is described in a specific embodiment in the specification, if no new information is disclosed.

Case: AP Racing Ltd v Alcon Components Ltd [2014] EWCA Civ 40.

First published in the March 2014 issue of PLC Magazine and reproduced with the kind permission of the publishers.  Subscription enquiries 020 7202 1200.