Buckman Laboratories (Pty) Ltd v Bromine Compounds Limited

The respondent (Bromine Compounds Limited) was the patentee of SA Patent 92/4018 entitled 'Process and Compositions for the Disinfection of Waters' with a priority date of 3 June 1991. The patent claimed a process for killing microorganisms and controlling biofouling in high chlorine demand circulating waters by mixing two components - an oxidant in the form of a chlorine precursor in solution and an ammonium salt in solution - thereby forming a biocidal mixture (chloramine), and adding it immediately to the water system to be treated. The respondent instituted action against the appellant (Buckman Laboratories) for patent infringement in the court of the Commissioner of Patents. It was common cause that if the patent was valid, the appellant was infringing it by using the claimed process at paper mill plants. The appellant counterclaimed for revocation of the patent on grounds of lack of novelty and lack of inventive step. The Commissioner of Patents (Southwood J) granted absolution from the instance on the counterclaim and interdicted the appellant from infringing certain claims. The appellant appealed with leave.

• Whether the patent should be revoked under section 61(1)(c) of the Patents Act 57 of 1978 on the ground that the invention did not involve an inventive step as required by section 25(1)
• Whether the invention was obvious to a person skilled in the art having regard to the state of the art immediately before the priority date
• What constituted the inventive step in the patent claims

The appeal was upheld with costs including costs of two counsel. The order of the court a quo was replaced with: (i) dismissal of the plaintiff's action with costs including costs of two counsel; (ii) granting of the defendant's counterclaim for revocation of SA Patent 92/4018, subject to provisional revocation; (iii) the revocation order to become fully operative if the patentee does not within one month file notice of an application to amend the patent, or if having filed such application, withdraws it - if an application is made and not withdrawn, the question of whether the revocation order is to be put into operation shall be decided at the hearing of such application; (iv) the plaintiff to pay the defendant's costs of the counterclaim including costs of two counsel.

An invention lacks an inventive step and is not patentable under section 25(1) of the Patents Act 57 of 1978 where: (1) all the essential elements of the claimed invention, save for one feature, form part of the state of the art immediately before the priority date; and (2) the distinguishing feature would have been obvious to a person skilled in the art as a matter of common sense, having regard to the state of the art. The fact that a patented process works or has not been previously implemented does not establish inventiveness where the combination of known elements would have been obvious to the skilled person.

The Court noted that the inventor (Dr Ayala Barak) was available to testify and a summary of her expert evidence had been delivered, but the respondent chose not to call her. The court a quo nevertheless had regard to her summary to determine what the inventive step was claimed to be. The Supreme Court of Appeal implicitly criticized this approach by noting that according to the summary, the invention aimed to produce an 'unstable biocide' contrary to conventional wisdom, but observed that the patent specification made no mention of stability, indicating that stability was not a feature of the patent at all. The Court also noted it was asked to deal with claims dependent on claims 1 and 14, but declined to do so as it would be an academic exercise given the invalidity of the independent claims.

This case provides important guidance on the application of the inventive step requirement under section 25 of the Patents Act 57 of 1978. It demonstrates that where all the essential elements of a claimed invention are disclosed in the prior art, and the only distinguishing feature would have been obvious to a person skilled in the art as a matter of common sense, the invention will be invalid for lack of inventive step. The case illustrates that the mere fact that a process works or has not been previously used in a particular industry does not establish inventiveness if the combination of known elements would have been obvious. It also confirms the principle that courts will examine what constitutes common sense in the relevant technical field based on expert evidence. The case further illustrates the proper approach to defining the state of the art and the skilled addressee when assessing inventive step.