The High Court ruled that representations by a patentee or its representatives about what a patent means are inadmissible to help construe the patent. The decision concerned an admissibility issue in a dispute between three Ranbaxy companies and Warner-Lambert Company over an Irish patent for the cholesterol drug Lipitor.
The plaintiffs seek a declaration that their proposed product would not infringe the Irish patent, No. 6014. They say the patent protects only certain equal mixtures of chemical compounds, known as racemates. Warner-Lambert disputes that interpretation and says the patent covers a wider range, including individual enantiomers and mixtures.
The plaintiffs sought documents concerning corresponding US, European and Danish patents, including patent office records, material used in US litigation and internal documents about the patent’s scope. They argued that earlier statements by Warner-Lambert or its representatives could show how a skilled person would understand the patent, and could amount to admissions against interest. Warner-Lambert argued that the documents reflected the patentee’s own views and were irrelevant to construing the Irish patent.
Mr Justice O’Sullivan held that the requested representations were, in substance, evidence of the patentee’s or its agents’ thoughts and intentions. He found that such material could not be used to determine the meaning of the patent, which is a question of law for the court. He distinguished an English case involving objective information about experiments, and did not accept that the principle allowing admissions against interest made the representations admissible in this context.
The judgment decided only whether the requested material was admissible. It did not determine the patent’s meaning, whether the plaintiffs’ product infringed, or whether the documents should ultimately be discovered. The judge left open the issue of discovery “de bene esse” for the judge dealing with the discovery motion, and said the plaintiffs could still make submissions on that point.