Be Careful What you Say at the EPO – Contested Proceedings Can Create Estoppel

There is no recognised doctrine of ‘file wrapper estoppel’ in UK patent law. If a patent proprietor has convinced the UK Intellectual Property Office (UKIPO) or the European Patent Office (EPO) to grant a UK patent on the basis of a particular claim construction, the UK courts are free to construe the same claim differently. The lack of this doctrine benefits those patent proprietors involved in litigation who feel that they must now argue for a different claim construction in order for their patent to be held infringed and/or to be held valid.

However, the recent decision of the UK Patents Court in Monsanto v Cargill, (10 October 2007) indicates that an interpretation placed on a claim by an EPO Technical Board of Appeal (TBA) in opposition proceedings is very relevant, should the same construction point arise during UK litigation.

The patent was concerned with enzymes, referred to as EPSPs, which, if expressed in a plant, conferred resistance to the herbicide “Round Up” (trade mark), resulting in an improvement to crops. Cargill bought soya beans in Argentina grown from seed carrying the gene in question, manufactured meal using the soya beans and imported a cargo of 5,000 tonnes of the meal into the UK. The vast majority of soya bean meal exported from Argentina came from seeds carrying a gene for an enzyme called CP4R, generally referred to as “Round Up Ready” seed.

In opposition proceedings, the EPO accepted a narrow interpretation of the phrase ‘Class II EPSPS enzyme’ contended by the opponent Cargill (which imported into the meaning a certain contrast with Class I enzyme set out in the specification). It seems that this was also the interpretation preferred by the proprietor Monsanto. In its decision, the EPO Board of Appeals disposed of an allegation of anticipation on the basis of this interpretation.

In the UK litigation, Monsanto argued for a broader interpretation of the phrase for the patent to be found infringed. The Court accepted that Monsanto was entitled to ‘argue in this Court for a different interpretation’ and also accepted that the House of Lords had made it clear that ‘reference to the EPO file is discouraged’ for the purpose of claim construction. Nevertheless, the Court went on to say

Here we are considering an interpretation arrived at in contested proceedings by a Board of Appeal of the EPO which should be treated with respect. I think one needs a good reason to depart from an interpretation placed on a claim by a Board of Appeal in contested proceedings and which forms part of one of the grounds of the decision.

In its judgement, the Court agreed with the construction adopted by the Board of Appeal and hence held that the patent was not infringed.

In any event, mere importation of meal made from plants that were descended through many generations from an original “Round Up Ready” soybean plant was not an infringement of a claim to “A method of producing genetically transformed plants” because the meal was not the direct product of the original transformation. The product was just soybean meal with no special intrinsic characteristics from one of the generations of plants.

Comment

In our Autumn 2002 edition of this newsletter, we said every practitioner must be wary of the doctrine of prosecution history estoppel, not merely because a foreign jurisdiction might consider evidence from a file history, but because we cannot predict the circumstances in which the file history may some day influence the Court. At that time we made reference to a Dutch case (Ciba-Geigy v. Oté Optics), and a UK case (Rohm & Haas v. Collag). In the latter case, the Court of Appeal referred to a letter filed by the patentee during prosecution to clarify the meaning of a claim.

Here, now, we have a case in which the UK Patents Court is willing to attach great significance to an interpretation accepted in contested (Opposition) proceedings by an EPO Board of Appeal.