Anan Kasei Co. Ltd & Anor v Molycorp Chemicals & Oxides (Europe) Ltd

For obviousness, the skilled person must be identified by reference to the technical problem addressed by the patent. A prior-art process directed to mixed oxides will not ordinarily make a claim to pure ceria obvious where the prior art gives no reason to make that substitution or to expect the claimed properties. The possibility that an unrecognised advantage might result does not itself establish obviousness. A product claim defined by desirable properties is not insufficient merely because the boundary of those properties may be difficult to determine, provided the patent discloses a general principle enabling the claimed result. The phrase “consisting essentially of” permits other components which do not materially affect the essential characteristics of the product.

The claimants owned, or exclusively licensed, the UK designation of a European patent for ceric oxide with specified surface-area and related properties. They alleged that the defendant’s products infringed claims 1 and 3 to 5. The defendant counterclaimed for invalidity of claims 1 to 5 on grounds of obviousness over US patent No 5,712,218, anticipation by an earlier ceric oxide product, and insufficiency.

The anticipation case was not pursued at trial. The principal issues were whether the skilled person would have adapted the prior art, which concerned mixed cerium-zirconium oxides, to produce pure ceria with the claimed properties; whether “consisting essentially of ceric oxide” was insufficient; whether the claims were impermissible broad “free beer” claims; and whether the defendant’s products fell within the claims.

1. Obviousness. The applicable approach was the four-stage test reformulated in Pozzoli: identify the skilled person and common general knowledge, identify the inventive concept, identify the differences from the prior art, and determine whether those differences would have been obvious.
2. The skilled person was a person particularly interested in the purification of vehicle exhaust gas. The relevant common general knowledge and technical context were therefore those of automotive catalysis, rather than the wider field of catalysis generally.
3. The prior art, Chopin, was directed principally to mixed oxides and their thermal stability. Although it used a method which could produce pure ceria in one comparison, it gave no indication that the resulting pure ceria had the claimed properties or was of independent interest. The evidence that the skilled person would select the patent’s process parameters was affected by hindsight and was given little weight.
4. The obviousness attack therefore failed. The skilled person would not have ignored the teaching of Chopin and adapted it to produce pure ceria falling within claim 1. It was unnecessary that the skilled person should foresee or appreciate an advantage for that advantage to count, but the necessary prior-art route to the claimed product had not been established.
5. Insufficiency. “Consisting essentially of ceric oxide” was construed in accordance with the settled European Patent Office approach. Other components could be present provided they did not materially affect the essential characteristics of the composition. Difficulty in identifying a precise borderline was a “fuzzy boundary”, not a true insufficiency. The skilled person could measure the claimed surface area, and the claims were not insufficient on that ground.
6. The claims were not impermissible “free beer” claims. The patent disclosed a general principle and a range of conditions for achieving the claimed properties. Nor did the absence of an express upper numerical limit make the claims insufficient; the enabled upper limit could be identified by routine trial and error.
7. The anticipation attack was not pursued. The defendant’s products fell within the numerical limits of claims 1, 3, 4 and 5 and, on the balance of probabilities, contained no relevant additives that prevented them from consisting essentially of ceric oxide. Those claims were infringed. Claims 1 to 5 were valid.