SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Limited [2011] FCA 452

A recent decision of the federal Court has reaffirmed the role of common general knowledge in assessing validity of an innovation patent.

FACT OF THE CASE

The relevant technology was treatment of waste (tailings) produced during processing of mined material. Ciba Specialty Chemicals Water Treatments Limited (‘Ciba’) was the owner of five innovation patents (‘the Patents’) covering the use of flocculants, in the form of water-soluble polymers, as part of this treatment process.

SNF (Australia) Pty Ltd (‘SNF’) brought proceedings for revocation of the Patents for invalidity on various grounds, primarily lack of novelty and lack of innovative step. Ciba cross-claimed for infringement of three of the Patents, alleging that SNF had used an infringing process at three mine sites in New South Wales. The case was heard before justice Kenny in the Federal Court.

The claims of the Patents required the addition of “an effective rigidifying amount of an aqueous solution of a water-soluble polymer” to the tailings, and novelty hinged on whether this was disclosed in one of a number of prior art documents and instances of prior public use. SNF accepted that if the Patents were valid, they had been infringed.  

THE DECISION

Novelty

Kenny j considered that, given the practical nature of the problem addressed by the Patents, the greater hands-on experience of Ciba’s expert witness in relation to the treatment of mining waste made his evidence more persuasive than that of SNF’s expert, whose knowledge in this respect was more theoretical. Accordingly, Her Honour accepted Ciba’s submissions that “rigidification” was distinct from settling and sedimentation as disclosed in the prior art. Her Honour also held in view of the expert evidence that addition of polymer particles (whether in solid form or in an emulsion) to the tailings, as disclosed in the prior art, was not the same as addition of an aqueous solution of water-soluble polymer.  

Innovative step and the role of common general knowledge

Kenny j, referring to her earlier judgment (sitting as part of a Full Bench) in the Dura-Post case (Dura-Post (Aust) Pty Ltd v Delnorth Pty Ltd [2009] FCAFC 81, see our IP Update September 2009), set out the test for innovative step as requiring the court to ascertain:  

  • the invention “so far as claimed in any claim”;
  • the person skilled in the relevant art;
  • the common general knowledge of the person skilled in the art as it existed in Australia before the priority date; and
  • whether, when considered from the perspective of the skilled person, in the light of that common general knowledge, the invention as claimed only varied from the prior art in ways that make no substantial contribution to the working of the invention as claimed.

In the present case, the evidence of industry witnesses was that before the priority date, it was known that polymer could be added as flocculant in a number of ways, including as powder, in emulsions or aqueous solution, and that they had for some years regularly added flocculant in aqueous solution to tailings slurries.  

In view of the expert evidence, Kenny j held that:

  • the form in which the polymer was added would have a material effect on how the process worked, and that the claims thus had an innovative step over prior art which disclosed addition of particulate polymer or polymers in emulsion; and
  • improved rigidification had significant industrial advantages which conferred an innovative step over prior art which disclosed settling and sedimentation. 

 SNF noted that the Patents did not contain any specific indication of any advantage of the use of polymers in solution, as opposed to in an emulsion. However, the mere absence of such a statement in the specification was less relevant than the expert evidence to the effect that the difference was significant.

COMMENTARY

The decision makes it clear that an assessment of innovative step, distinct from that of inventive step of standard patents, does not involve a combination of prior art information with the common general knowledge. Rather, the common general knowledge is to be used solely to identify any differences between the claimed invention and the prior art, and to assess whether these differences materially affect the working of the invention.

The case also emphasises the critical role of expert evidence in assessing patent validity in Australia, and in particular the need to take into account the nature of the invention (and thus the person skilled in the art) when choosing an expert witness.