Bateman Equipment Ltd and Another v The Wren Group (Pty) Ltd

The registered proprietor of patent 93/6167 (the respondent) instituted infringement proceedings against the appellants in the Court of the Commissioner of Patents. The appellants filed a counterclaim for revocation of the patent, alleging invalidity due to lack of novelty, obviousness, and lack of clarity. In response, the patentee applied for amendment of the patent specification in terms of section 51(9) of the Patents Act 57 of 1978. Mynhardt J, sitting as Commissioner of Patents, granted the application despite wide-ranging objections. The appellants appealed with leave of the court below. The patent concerned a process and apparatus for treating a suspension of solid particles in a carrier liquid using gravity settling without moving parts, progressively thickening the suspension and separating clarified liquid from slurry.

• Whether section 51(9) of the Patents Act requires 'full reasons' for an amendment application (as required under section 51(1) for applications to the Registrar)
• Whether the amended claims 1 and 7 (renumbered as claim 6) lack a fair basis in the specification as required by section 51(6)(b)
• Whether certain terms in the amended claims are unclear and would render them invalid and subject to revocation under section 61(1)(f)(i)
• Whether the specification provides sufficient clarity regarding the demarcation of different settling regions
• Whether the conduit requirement in the amended claim 6 is inconsistent with the original specification

Appeal dismissed with costs, including costs of two counsel.

1. Section 51(9) of the Patents Act 57 of 1978, governing patent amendments during pending court proceedings, does not require 'full reasons' as a jurisdictional prerequisite, unlike section 51(1) which governs applications to the Registrar. Under section 51(9), the sufficiency of reasons is at most a discretionary factor the court may consider in deciding whether to grant the amendment. 2. Patent claims must be interpreted through the eyes of a skilled addressee in the relevant art, who is expected to use reasonable skill and intelligence and not adopt an attitude of 'studied obtuseness'. Claims must be read as a whole and, where words permit, interpreted consistently with the description of the problem and solution in the body of the specification. 3. Patent claims require 'reasonable certainty' as to their scope, not mathematical precision. The mere fact that simple, non-inventive test trials or experiments may be necessary to ascertain whether a particular item falls within the ambit of a patent does not invalidate the patent. 4. Under section 51(6)(b), amended claims must be fairly based on matter disclosed in the original specification. The objective is to prevent a patentee from claiming ex post facto something not contained in the original disclosure. This requirement should be interpreted broadly and liberally to permit any fair amendment which has already in substance been disclosed, even if not exemplified. 5. Claims may extend beyond specific examples or embodiments disclosed in a specification, provided they do not exceed the general or generalized disclosure of the invention.

The Court expressed approval for the approach of Van Dijkhorst J in Deton Engineering (Pty) Ltd v McKelvey (unreported, 11 June 1997), who held that issues of continuing invalidity should be ventilated in revocation proceedings rather than amendment proceedings to keep the latter relatively simple and prevent multiplication of issues. Harms JA noted this was a commendable approach, though Mynhardt J did not follow it as the judgment became available only after argument commenced. The Court also observed that it is in the public interest both that inventors should be encouraged to disclose their inventions in exchange for patent grants, and that patents should be capable of rectification or validation by amendment. The judgment questioned whether overly formalistic patent amendment litigation was being used as a delaying tactic. Regarding the Mond Nickel three-part test for fair basis, Harms JA expressed reservations about whether there are truly three separate enquiries or whether they are essentially the same question in different forms, noting the difficulty in envisaging how a specification can describe something in broad terms on which it is wholly silent, or how something inconsistent can simultaneously fall broadly within its terms.

This case is significant in South African patent law for clarifying the distinction between amendment procedures under section 51(1) (applications to the Registrar) and section 51(9) (applications during pending court proceedings). It established that 'full reasons' are not a jurisdictional requirement for amendments under section 51(9). The judgment reinforced the approach to patent interpretation that rejects overly formalistic or pedantic readings ('studied obtuseness'), emphasizing that claims must be read holistically through the eyes of a skilled addressee. It clarified the 'fair basis' requirement under section 51(6)(b), holding that amendments are permissible if they do not claim ex post facto matter not in the original disclosure, and that claims may extend beyond specific examples if consistent with the general disclosure. The case also confirmed that reasonable certainty, rather than mathematical precision, is the required standard for claim clarity, and that the need for simple non-inventive tests to determine claim boundaries does not invalidate a patent. The judgment reflects policy considerations favoring patent amendments as being in the public interest for validating and rectifying patents.