Daesang Corporation and Daesang Europe (BV) v Ajinomoto Co. Inc.

Author:Mr Huw Evans
Profession:Wragge & Co LLP

This case concerned an application for revocation of a patent. There were invalidity attacks based on anticipation, obviousness and insufficiency. Laddie J described the patented invention as very simple but went on to uphold the validity of the patent.


Ajinomoto own a European Patent claiming a process for the production of aspartame on an "industrial scale". Aspartame is a low calorie sweetener which is used in a variety of food and drinks. The claimed invention relates to the purification of aspartame by using a static crystallization process on an industrial scale.

Ajinomoto had sued Daesang in the Netherlands for infringement of the Dutch and UK European patents. Daesang applied for revocation of the European (UK) patent ("the Patent").

The attack on the Patent was on three grounds - insufficiency, anticipation and obviousness.


Daesang argued that terms in the claims such as "industrial scale" were ambiguous and that this gave rise to an insufficiency attack. The attack was not run as the primary attack on invalidity but rather as a squeeze against a narrow construction of the prior art.

Laddie J added that although the various terms use imprecise, no one in the art would have any difficulty in knowing what they meant. In his view the claimed process was extremely simple, namely the use of a static crystallisation process instead of an agitated crystallisation process. Laddie J therefore dismissed the insufficiency attack.

Laddie J warned that as with obviousness, when considering anticipation it is necessary to be aware of the dangers of hindsight: "The smaller the invention, the easier it is to analyse, explain and discredit it".


There was only one item of prior art relied upon for both the anticipation and obviousness attacks, Japanese laid-open patent, as "JP '267".

The teaching of JP '267 related to a method of purifying aspartame by using a combination of methods all of which incorporated a crystallisation step. The specification of JP '267 said its objective was to provide an industrial method to purify aspartame.

It was accepted by both parties that the general teaching of JP '267 disclosed nothing about the method of crystallisation. However, Daesang argued that static crystallisation was at least inferred.

Laddie J held that JP '267 did not give clear and unmistakable directions to use static crystallisation, and even if it did there were no such instructions to do so on an...

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