Case: Catnic Components Ltd v Hiller and Smith Ltd [1982] RPC 183
Outcome: referred to
It is, however, necessary to guard against an unduly strict literal approach since, in some circumstances, such an approach may be inappropriate. By way of illustration, see Catnic Components Ltd v Hiller and Smith Ltd [1982] RPC 183 at 242 per Lord Diplock. That case illustrates circumstances in which the strict literal approach was considered by the House of Lords to be inappropriate. 44 With these principles in mind, I turn now to the construction of the claims in the present case. 45 The construction question in the present case focuses on Claim 7 of the Complex Patent. As discussed above, Claim 7 is a claim for a complex and not a product or a method for a product. It claims a monopoly for: "(7) A stable soluble alkaline calcium phosphate complex, which has been formed at a pH greater than 7, including phosphopeptide stabilised amorphous calcium phosphate or a derivative thereof wherein the said phosphopeptide includes the amino acid sequence Ser(P)-Ser(P)-Ser(P)-Glu-Glu." 46 Professor Dawes explains Claim 7 in this way. He points out that a "complex" is a combination of two or more components in which there is an interaction between the components. The calcium phosphate complex in this claim is alkaline. This means that, as it exists, it has a pH of more than 7. There is an additional integer that the calcium phosphate must be formed at a pH greater than 7. This goes to the manufacture of the complex, which must retain a pH greater than 7 after creation and when examined. The phosphopeptide referred to is a chain of amino acids which has phosphorylated amino acids. The phosphopeptides stabilise calcium phosphate in a non-crystalline form by inhibiting it from converting into a crystalline form and precipitating out of solution. Amorphous calcium phosphate is usually not stable as it tends to convert to crystalline forms of calcium phosphate. Amorphous calcium phosphate is bio-available in that it can dissolve and release calcium and phosphate for depositing on teeth. The calcium and phosphate ions, due to their size, can diffuse through surface enamel over a sub-surface caries lesion. The pores on the surface enamel are larger than the charged ions and will not impede the diffusion of calcium or phosphate ions through the enamel. By contrast, crystalline forms of calcium phosphate present in the mouth under normal oral conditions cannot diffuse into the teeth, because the crystals are too large to diffuse through the pores in the enamel. These forms of calcium phosphate are therefore not bio-available. 47 The case for NSI is that, as a matter of language, the subject of the claim is the "complex" referred to, which is defined in the claim. NSI says that the complex is required to be "stable", "soluble", "alkaline", to "include calcium phosphate" - which is "formed at a pH greater than 7" - and to "include phosphopeptide which stabilises amorphous calcium phosphate or a derivative thereof". 48 In my view, the last descriptor referred to by NSI does not accurately reflect Claim 7. The final element of Claim 7 refers to phosphopeptide stabilized amorphous calcium phosphate or a derivative thereof. It is the stabilized amorphous calcium phosphate or derivative which is included and not merely the phosphopeptide. The expression is a composite. 49 NSI also submits that the phosphopeptide must include the Cluster Sequence. NSI says that it is common general knowledge among relevant addressees that phosphopeptides containing the amino acid Cluster Sequence are derived from proteins and, in particular, caseins.