Occlutech GmbH v Aga Medical Corp

Patent claims must be construed according to the language chosen by the patentee and the meaning which the skilled reader would give it. A limitation is not to be disregarded merely because its purpose is unclear or its inclusion appears odd. Where a claim requires clamps at opposite ends of a device, that requirement cannot be replaced by a functionally equivalent arrangement with a clamp at only one end. Welding or a loose sleeve does not constitute clamping where the patent distinguishes those methods from physical binding. A device may be generally dumbbell-shaped without strict requirements as to the relative length of its central portion.

Occlutech sought declarations that two medical occluder devices did not infringe AGA’s patent and sought revocation for obviousness. AGA counterclaimed for infringement and joined Occlutech’s importer. The obviousness attack relied on a single international patent application, referred to as Boston Scientific. The infringement issues concerned the construction of “clamps”, the requirement for clamps at opposite ends, and the meaning of “generally dumbbell-shaped”. The court also considered prior German and Dutch decisions concerning the same patent.

1. Obviousness. Applying the approach in Pozzoli Spa v BDMO SA [2007] FSR 372, the Boston Scientific disclosure differed materially from the patent in suit. It used knitted rather than braided fabric, did not disclose the relevant dumbbell shape in the necessary sense, and did not disclose clamps at both ends to form a blockage. The patent was not obvious and the revocation claim failed.
2. Construction. The language of the claims was critical. Following the principles derived from Kirin-Amgen Inc v Hoescht Marion Roussel Ltd [2005] RPC 9 and STEP v Emson Europe Ltd [1993] RPC 513, an apparently unusual limitation could not be ignored without a rational basis.
3. “Clamps” meant objects exerting a physical fixing or binding force on the strands so that they did not unravel. Welding, soldering and similar adhesive methods were expressly treated by the specification as alternatives to clamping. The temporary copper wire, loose nitinol sleeve, welding operation and adaptor in the Occlutech devices therefore did not provide the claimed clamps.
4. The claims required clamps at the opposite ends of the device. The closed sock-end of the Occlutech devices was not a clamp. The court declined to extend the claims by using the Improver Corp v Remington Consumer Products Ltd [1990] FSR 181 questions where the claim language had already been construed; in any event, strict compliance was required.
5. “Generally dumbbell-shaped” was a broad, figurative description of two wider portions separated by a narrower portion. The Occlutech devices fell within that description. The added-matter objection consequently failed.
6. The declarations of non-infringement succeeded. The infringement counterclaim failed. The patent survived the revocation attack.