Case: Ranbaxy UK Limited v Warner-Lambert Company [2005] EWHC 2142
Outcome: cited
Claim 5 of the 981 Patent uses the (+/-) sign so as clearly to indicate that claim 5 was confined to racemic mixtures. That descriptor is not applied to claim 1 or other claims. Arguably, this provides a slight indication that claim 1 was not intended to be limited to racemic mixtures. It also shows that the patentee was aware of particular means by which claims could be limited to a claim to a racemic mixture. This factor is not irrelevant because it is consistent with other indicators that the patent does not exclude the individual enantiomers. However, I am not disposed to attach significant weight to it: see Ranbaxy (UK) Ltd v Warner-Lambert Company [2006] EWCA 876 ( 'Ranbaxy UK' ) at [30] per Jacob LJ; see also the warnings given about the incautious use of the expressio unius maxim of construction in Houssein v Under Secretary, Department of Industrial Relations and Technology (NSW) [1982] HCA 2 ; (1982) 148 CLR 88 at 94 and Wentworth v NSW Bar Association [1992] HCA 24 ; (1992) 176 CLR 239 at 250. 150 In Ranbaxy UK , the Court of Appeal held that Warner-Lambert's European Patent EP (UK) 0247633, on its proper construction, claimed both the individual enantiomers and the racemate of structural formula I of claim 1. In doing so, the Court of Appeal affirmed the decision of Pumfrey J: [2005] EWHC 2142 (Patents). The patent in suit was relevantly identical to the 981 Patent. Ranbaxy's construction arguments were also very similar to the arguments advanced in this case. The Court rejected all of those arguments. 151 In the leading judgment, Jacob LJ said at [19]: '... Overshadowing everything is the fact that the skilled reader would know that the R,R-enantiomer was the form which had all or by far the preponderance of the pharmaceutical activity. He would expect the patentee to know that too. And he would know that the patent claim was drafted by someone who knew what its function was to "demarcate the invention" (per Lord Hoffmann in Kirin-Amgen at p.185). There simply is no rational basis for supposing that the patentee would want to exclude the pure enantiomer which he would have known was the substance which really mattered.' A little later in his judgment, his Lordship said at [22]: 'Moreover the actual drawing of formula I and of X shows what is, strictly speaking, just the R,R enantiomer (compare drawing A on Annex A with Formula I). It was common ground that in practice chemists are not precise: that a figure showing a particular structure may mean, in context, a racemate. The Judge held that, in the context of the patent, Formula I would have been understood to show the racemate. However, I can think of no rational reason why it should mean only the racemate in the context of this patent. It is a patent whose big idea is not about stereochemistry but about a novel substitution. The only reference to stereochemistry excludes the "cis-form" of the compounds (which would be both cis-enantiomers) but not the trans- form (which would be both trans-enantiomers). And above all the skilled reader would know that the form giving most if not all activity was the R,R form.' 152 Neuberger LJ reasoned along similar lines at [49]: 'Subject to the point considered in the next paragraph but one, it seems to me clear that the formula in claim 1 must be a reference to the enantiomers as well as the racemic mixture. As the notional addressee of the patent, the relevantly skilled person, would appreciate, it would have been absurd for the patentee to have limited his claim to the racemic mixture. Given that one of its two constituent enantiomers would have been, at best less effective than, or, at worst, ineffective and detrimental to the effectiveness of, the other enantiomer, it would make no practical sense to construe the formula as extending only to the racemic mixture and not to the latter enantiomer. In this connection, I should refer to the Judge's finding that the relevantly skilled person would know how to resolve the racemate (i.e. how to isolate the (more) effective enantiomer) and he would know that this would be generally appreciated by those skilled in the art. That may well be of crucial significance. First, in terms of teaching, the patent is thereby not rendered insufficient if it claims the enantiomers, notwithstanding any express teaching as to how to resolve the racemic mixture. Secondly, the finding underlines the commercial unreality, actual and as perceived by the skilled person, of the contention that the claim does not extend to the enantiomers.' 155 Both Warner-Lambert and Ranbaxy accepted that this decision was persuasive authority in this Court. Senior counsel for Ranbaxy sought to distinguish the case on the basis that it was critical to the decision that no explanation or possible reasons had been advanced as to why the patentee would wish to exclude the individual enantiomers from the scope of claim 1 in the specification. In this regard, senior counsel pointed to the question that Pumfrey J posed in [39] of his reasons: 'a proper approach to construction of this claim is to ask why the patentee, who has covered a two-element composition for use in a drug, would wish not to cover one element of that combination which any reader would know was the effective element and which could be isolated using routine techniques'. Pumfrey J then drew a distinction between an omission that was surprising but for which the patentee might have reasons, and on the other hand an omission that is both surprising and would in the eye of the reader immediately deprive the patent of any commercial effect. Senior counsel for Ranbaxy argued that on this point there was an important distinction between the evidence advanced in the English proceedings and the evidence before this Court. He submitted that Ranbaxy had identified a number of possible reasons why the specification and claims had been drafted so as to exclude the individual enantiomers, in particular the fact that Warner-Lambert proposed to go to market with a racemate and may have contemplated practical difficulties in producing a single enantiomeric drug on a commercial scale. He did not point to any other significant differences in the evidence before the English Court. 156 The suggested distinction between the two cases is illusory. It is clear from the judgment in the Court of Appeal that Ranbaxy argued that there were reasons why the patentee would want to limit the monopoly to the racemate, including the fact that the patentee had done no work with the enantiomer, had no data on it, at the date of the patent many chiral pharmaceuticals were in racemic form, and the perception of a skilled man would be that the SS enantiomer had little or no effect: at [18] and [19]. In my opinion, the Court of Appeal's decision strongly supports the construction which I have adopted of the 981 Patent. 162 Ranbaxy has admitted that its product, with its active ingredient atorvastatin calcium, falls within the scope of claim 6 of the Enantiomer Patent. Therefore, the only matters in dispute between the parties in relation to the Enantiomer Patent are as to its validity. The validity of patents that are equivalent to the Enantiomer Patent has been litigated in England, the United States and Canada. However, the decisions in these jurisdictions do not shed any light on the invalidity issues that were contested before me: see Ranbaxy UK at [32] and [40]-[41] per Jacob LJ; Ranbaxy UK Limited v Warner-Lambert Company [2005] EWHC 2142, at [62] per Pumfrey J; Pfizer Inc v Ranbaxy Laboratories Limited , supra; Pfizer Inc v Ranbaxy Laboratories Ltd 405 FSupp2d 495 (D Del 2005) at 512-513 [22]-[27], 518 [32], 519 [35] and 520-525 [36]-[43]; see also Pfizer Canada Inc v The Minister of Health [2006] FC 1471.