Anyway, getting back to the case. It was an appeal from Mr Justice O’Sullivan on a procedural point. He had decided on 8 July 2005 to exclude from the evidence correspondence between the respondent's patent agents and the European and Danish patent offices on the scope of the patents for which they were applying. The point arose in a preliminary issue as to whether those documents should be discovered. It was alleged that those letters contained evidence that Warner Lambert sought patent protection only for racemates. The reason the Ranbaxy companies wanted that evidence in was that they had applied for a declaration under the Irish equivalent of s.71 of our Act that their anti-cholesterol drug did not infringe Warner Lambert's patent because their drug was single enantiomer and not a racemate.
It seems to me that the strategy may have been to import into Irish patent litigation practice something like the US file-wrapper or prosecution history estoppel. Given the similarities between the Irish and English legal systems, a favourable judgment over there by judges of the callibre of Mr Justice McCracken and Mrs Justice Macken might have carried weight here.
The Ranbaxy companies argument was quite ingenious. They did not try to get it in as a statement of intention as would perhaps be the status of such a letters in America under the file wrapper estoppel doctrine - American lawyers, please correct me if I am getting the wrong end of the stick - but as evidence of "the opinions of persons skilled in the art as to the construction of the claims". They relied on the following dicta of Lord Justice Walker in Rohm and Haas Co & Another v Collag Ltd and another  EWCA Civ 1589 (29 Oct 2001) where the Court did not exclude a letter between Rohm & Haas's European Patent Department to the European Patent Office:
"The letter to the European Patent Office did not have the same status as published prior art identified in a specification, which is readily admissible. But it did contain objective information about and commentary on experiments which were conducted in response to official observations, and it could be of assistance in resolving some puzzling features of the specification. Although the prosecution process may sometimes superficially resemble a process of negotiation between the applicant and its advisers and the officials who scrutinise the file, it is not the sort of commercial negotiation which is still rigidly excluded in the construction of a written contract (see Investors Compensation Scheme v West Bromwich Building Society  1 WLR
896, 913). Had it been necessary for the judge to take account of the letter in order to resolve the issue of construction, I consider that he would have been entitled to do so."
The Irish Supreme Court bought none of this argument and in my very respectful submission they were right not to do so. They distinguished the case before them from the Lord Justice Walker's dicta partly on the ground that there was no evidence as to the qualifications or experience of Warner Lambert's patent agents but mainly on the ground that the correspondence was written not from the point of view of an independent expert but was written as part of submissions made on behalf of the patentee in relation to the invention itself. Unlike the letter in the Rohm & Haas case, this correspondence did not deal with experiments, was not made in the course of the application for this patent and the correspondence in fact took place after the priority date. As Mr Justice McCracken concluded:
"the fatal flaw in the Appellants’ case is that these letters were written by persons acting on behalf of the Appellants and who were in fact their agents for the purpose of entering into this correspondence. They were not written by such agents acting on their own behalf, but acting on behalf of the Appellants. They were submissions on the Appellants behalf being made to the several patent offices and as such were intended to and did reflect the views of the Appellants. They expressed the construction which the appellants wished to put upon the claims in the patent in suit. As such, they were in reality expressions of the opinion of the patentee as to the construction of the claims and accordingly they are clearly inadmissible."
However, in reviewing at some length the law on the European approach to patent claims interpretation - that is to say the application of the Protocol to art 69 of the European Patent Convention - they hinted at the real reason which is that there really is no place for extrinsic evidence on a question of construction. The preliminary draft revisions to the European Patent Convention before the diplomatic conference in 2001 contained a provision for representations before the patent office to be taken into consideration for the purpose of interpretation in the Protocol but it was dropped. So long as interpretation in Europe is anchored (albeit remotely in the case of figurative interpretations) to text there really should be no need for evidence of the kind that was rejected here.
Had the case gone the other way, patent litigation in our adversarial system would have been even more expensive. It would have been even more difficult for SME and independent inventors to enforce their patents. That would have meant even less patent litigation work in England and Ireland.
For more stuff on the Ranbaxy litigation around the world see Ranbaxy Case: A US Perspective 13 Oct 2005 and IP Case Law Update - Patents: Ranbaxy UK Ltd and another v Warner-Lambert Co.  EWHC 2142 (Patents) (12 Oct 2005) and Lipitor Again 15 Oct 2005.