UK – Schlumberger v. Electromagnetic Services

Posted: July 29th, 2010

Schlumberger v. Electromagnetic Services, Court of Appeal, London, UK, 28 July 2010, [2010] EWCA Civ 819

The Court of Appeal has allowed Electromagnetic Services’ (EMGS) appeal of the decision of the Patents Court to revoke two of EMGS’ patents relating to the use of CSEM (Controlled Source Electromagnetic) surveying to detect oil and gas deposits under the sea.

It was common ground between the parties that the two patents in issue, EP (UK) 1 256 019 and EP (UK) 1 309 887, stood or fell together and so the appeal was concerned with EP (UK) 1 256 019 only. At the first instance trial, Mr Justice Mann had held the patent to be obvious on the basis of three pieces of prior art (Chave, MacGregor and Srnka) but rejected Schlumberger’s lack of novelty attacks based on Srnka and Yuan.


Lord Justice Jacob, who gave the leading judgment of the Court of Appeal, began his judgment by considering two questions of law. The first was whether the notional skilled team was the same for all purposes under the European Patent Convention and the second was a consideration of the place of secondary evidence. Lord Justice Jacob found on the first question that the skilled team need not be the same for all purposes and held that secondary evidence was not always of minor importance in respect of the second question.

Lord Justice Jacob rejected the obvious attacks based on Chave and MacGregor because the skilled team would not have realised that CSEM could be applied to the problems of detecting oil and gas deposits under the sea. The lack of novelty attack based on Srnka failed because the document did not have the necessary clarity to amount to a clear and unambiguous disclosure and the obviousness attack failed because the teaching disclosed in the document was very unclear and did not deal with conventional CSEM. The lack of novelty attack based on Yuan also failed as the disclosure did not fall within the scope of the claims and was not enabling.

Read the judgment (in English) here.

Head note: Rob Fitt

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