Daesang Corporation & Anor v Ajinomoto Co Inc

Patent claims are not invalid for ambiguity where the skilled person can understand the relevant expressions and the practical limits of the claims, even though those expressions are imprecise. A claim is anticipated only where the prior art gives clear and unmistakable directions to perform a process within the claim. Obviousness must be assessed without hindsight and by considering what the skilled person would have understood and done at the priority date. A laboratory disclosure does not make an industrial process obvious merely because routine investigations might eventually lead to the invention. Industrial scale includes bulk production, speed, reduced cost, and uniform and predictable quality.

Daesang Corporation and Daesang Europe B.V. sought revocation of Ajinomoto Co. Inc.’s European patent for an industrial process for purifying aspartame by static crystallisation. The patent claimed cooling a supersaturated aqueous solution without forced flow to produce a sherbet-like pseudo-solid containing bundle-like crystal aggregates, followed by conversion to a slurry and solid-liquid separation.

Anticipation and obviousness were alleged over Japanese Laid-open Patent Specification 167267, with obviousness also advanced by reference to common general knowledge. The central issues were whether the claims were ambiguous or insufficient, whether the prior art disclosed static crystallisation on an industrial scale, and whether the claimed process was obvious.

1. Disposition. The revocation claim failed. The patent was valid.
2. The expressions complained of, including “industrial scale”, “sherbet-like pseudo-solid phase”, “without effecting forced flow” and “bundle-like crystal aggregates”, were imprecise but intelligible to the skilled person. They therefore did not create an ambiguity invalidating the claims. The specification also gave a simple and sufficient method of carrying out the claimed process.
3. The inventive concept of claim 1 was essentially the industrial-scale crystallisation of aspartame from aqueous solution without forced flow. The other integers largely described inevitable results of that process, and the minimum precipitation requirement added little practical limitation.
4. Anticipation required clear and unmistakable directions in the prior art to carry out a process falling within the claims. Japanese Laid-open Patent Specification 167267 described purification and crystallisation, but gave no clear teaching of static crystallisation. Its laboratory examples did not establish that static crystallisation had been used, and in any event did not teach its use on an industrial scale.
5. Obviousness had to be assessed through the eyes of the skilled person at the priority date. The prior art and common general knowledge pointed towards agitated crystallisation because it promoted uniform cooling, narrower crystal-size distribution, speed, predictability and efficient separation. Static crystallisation was associated with serious operational disadvantages and was not the normal choice for commercial production requiring consistent crystal quality.
6. The argument that routine laboratory experiments would inevitably reveal the pseudo-solid and lead to the claimed process was hindsight reasoning. The claimed process was counterintuitive and far removed from the accepted approach. Claims 4 to 6 were also found independently valid, although the alternative findings concerning their obviousness if claim 1 failed were contingent.