Vericore Ltd v Vetrepharm Ltd & Anor

On an appeal from the Patent Office concerning patent validity, the appellate court should give great weight to the first-instance decision, particularly on factual findings based on oral evidence. A patent using the term “pyrethroid” is not confined to synthetic compounds where the technical meaning ordinarily includes natural pyrethrins and the patent contains no express limitation. “Treatment” of an infestation does not require a specified efficacy threshold unless the patent supplies one. For obviousness, the skilled addressee may comprise a team with the relevant technical expertise. Prior art indicating promising results and the need for optimisation may make a claimed use obvious, including use of a pesticide in a standard suspension where no technical obstacle is established.

Vericore Ltd appealed against a decision of the Comptroller’s delegate, Mr Dennehey, dated 18 March 2002, which held UK patent GB 2,270,261 invalid. Claims 1 and 4 were found anticipated, and all claims were found obvious over pleaded prior art. On appeal, Vericore maintained independent validity principally for claims 1, 6, 8 and 9.

The appeal challenged the application of the legal principles to the evidence. The central issues were whether “pyrethroid” was limited to synthetic compounds, whether the prior art disclosed a sufficient “treatment”, whether one thesis was publicly available before the priority date, the characteristics of the skilled addressee, and whether the claimed use was obvious.

1. The appeal was a rehearing under paragraph 16 of the Patent Practice Direction pursuant to CPR Part 52 rule 11 and CPR Part 49. The appellate court nevertheless gave great weight to the first-instance decision, especially on factual issues dependent on witness and expert evidence. The unchallenged findings on witnesses and primary facts were not reopened.

2. The term “pyrethroid” ordinarily included both natural pyrethrins and synthetic compounds. Although a minority used the term more narrowly, the patent did not expressly restrict the invention to synthetic compounds. The fact that its examples happened to use synthetic compounds did not establish such an intention.

3. “Treatment” did not impose a requirement that a particular percentage of sea lice be killed. The patent specified no efficacy threshold, and its examples did not consistently achieve the proposed 95 per cent level. Prior art reporting kill rates of 74 and 89 per cent therefore disclosed treatment within the claims and anticipated them.

4. The DSc thesis relied upon as D1 was prior art. The evidence established an intention to make it publicly available as soon as reasonably practicable after printing, with copies available for inspection before the priority date and without confidentiality restrictions.

5. The relevant skilled addressee would possess, or have access to, both fish-health and toxicological expertise. The prior art gave an adequate incentive to investigate synthetic pyrethroids, and the known toxicity did not remove the obviousness of trying them within an appropriate therapeutic margin.

6. Using a pesticide suspended in water was a standard mode of administration. The evidence did not support the proposed explanation that survival depended on avoiding contact with the fish’s gills. In light of the prior art’s promising results and suggestion of easier administration, claims 6, 8 and 9 were also obvious.

7. The appeal was dismissed. The Patent Office decision that the patent was invalid therefore stood.

• High Court (Chancery Division), Patents Court: appeal from the Patent Office decision dated 18 March 2002. The appeal was dismissed and the finding that the patent was invalid was upheld.