The original written description and claims for a patent application must be sufficiently clear and complete as to the inventive concept sought to be protected; otherwise, the patent subsequently granted may be revoked on the ground referred to as “added matter”. Whilst similar provisions in relation to “added matter” can be found in the Patents Ordinance (Cap 514) of Hong Kong (“PO”), the Chinese Patent Law, the European Patent Convention and the UK Patents Act 1977, this newsletter focuses on the provisions of PO to illustrate the significance of “added matter” to a patent application.

Introduction
A patent granted may be revoked on the ground that matter disclosed in the specification extends beyond matter disclosed in the application for the patent as filed (section 91(1)(d) of Patents Ordinance (“PO”))[1]. Further, divisional patent application[2] of both standard and short-term patent shall be invalid, again, if it extends the subject matter disclosed in the earlier application as filed (section 103(1) of PO). Amendments of standard patent at the pre-grant stage (section 103(2) of PO) or both standard and short-term patent at the post-grant stage (section 103(3)(a) of PO) shall also be invalid on the similar ground.[3] Such matters which extend beyond those disclosed in the application as filed are referred to as “added matters”.

Section 103 of PO is closely related to section 91(1)(d) of PO. The resultant patent granted shall be revocable under s.91(1)(d) if the followings are wrongly granted: (i) a divisional application disclosing “added matter” (section 103(1)); (ii) an amended standard patent application disclosing “added matter” (section 103(2)); or (iii) an amendment of the specification of a standard/short-term patent disclosing “added matter” (section 103(3)(a)).

The rationale is that an applicant should not be allowed (i) to improve his position by adding subject matter not disclosed in the original application as filed and (ii) to limit the extent to which an applicant can widen his claim for monopoly while preserving his priority. So, what amounts to an “added matter”?

What is “added matter”?
The English case of Bonzel (T) v Intervention Ltd (No 3) [1991] RPC 553 established a threefold test for “added matter” when deciding whether a patent granted should be revoked pursuant to s.72(1)(d) of the Patents Act 1977 in UK.[4] The task of court is: (1) to ascertain through the eyes of the skilled addressee what is disclosed in the application, both explicitly and implicitly; (2) to do the same in respect of the patent granted; and (3) to compare the two disclosures and decide whether the subject matter relevant to the invention has been added whether by deletion or addition.

A subject matter will be regarded as “added matter” unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly. On the other hand, if a feature is an essential element of an application filed, omitting such a feature will be regarded as disclosing matter which extends beyond that disclosed in the application filed and thus amount to an “added matter” too.[5]

In short, whether a matter is additional depends on whether a skilled man would, upon looking at that matter, learn anything about the invention which he could not learn from the original application as filed. Matter which the skilled person would certainly have known and does not need to be explained may be regarded as having been disclosed; and thus does not amount to an “added matter”. 

Examples of “added matter”
·          A divisional patent application specifying “at least one” conveyor in its claims, when its parent application specified “three” conveyors, was held to disclose matter extending beyond that disclosed in the parent application and thus an “added matter”.[6]

·          A guide wire lumen original stated in the patent application as “only about as long as a catheter balloon” was subsequently described as “relatively short” in the patent granted. Whilst “catheter balloon” was typically of merely 2 cm, the overall length of guide wire lumen in prior art was 135 cm long. It was held that the application filed did not disclose that the guide wire lumen could be much longer than a catheter balloon and thus matter disclosed in the patent granted amounted to “added matter”.[7]

·          To extract a feature (which was neither remarked on in the specification nor of significance to the person skilled in the art) of one of the preferred embodiments of the invention and insert it into a claim, while ignoring the other features of that embodiment, was not permitted on the ground of “added matter”.[8]

Conclusion
The potential problem of “added matter” means that the key inventive concept must be clearly and sufficiently disclosed in the original specification in the first place. If not, any attempt to add it by later amendment of the specification may be objected to by the examiner. The consequence is sometimes fatal, either that the key inventive concept would be excluded from the scope of protection, or even worse, where without such key inventive concept the whole patent application may lack inventive step in view of prior arts, then grant would be refused. Even if such “added matter” is not objected to before grant, it would become a vulnerable point for attack in infringement litigation or invalidation proceedings.  

To avoid unnecessary future challenges of a patent granted, applicants must be very wary that the original written description and claims should clearly cover the inventive concepts which are intended to be protected by the patent.

[1]     Also see section 72(1)(d) of UK Patents Act 1977; Article 138(1)(c) of European Patent Convention; and Rule 53(3) of Implementation Regulations of the Chinese Patent Law [2]     A divisional patent application is an application which subject matter is divided out of an earlier patent application filed. It is necessary when the earlier application involves two or more inventions that do not form a single inventive concept and thus the earlier application must be divided into separate applications to avoid the objection of plurality of inventions. [3]     Also see section 76 of UK Patents Act 1977; Article 123 of European Patent Convention; and Article 33 of Chinese Patent Law and Rule 43 of Implementation Regulations of the Chinese Patent Law [4]     Equivalent of section 91(1)(d) of Patents Ordinance (Cap 514) in Hong Kong [5]     Raychem Ltd’s Applications [1986] RPC 547; B&R Relays Ltd’s Application [1985] RPC 1 [6]     Van der Lely’s Application [1987] RPC 61 [7]     Bonzel (T) v Intervention Ltd (No 3) [1991] RPC 553 [8]     LG Philips LCD Co Ltd v Tatung (UK) Ltd [2007] RPC 21

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Important: The law and procedure on this subject are very specialised and complicated. This article is just a very general outline for reference and cannot be relied upon as legal advice in any individual case. If any advice or assistance is needed, please contact our solicitors.