DLP Limited v Coram UK Holding Limited

Facts

DLP Limited owns UK Patent No GB 2,446,666, titled "an electric shower-waste pump and control unit". The patent was filed on 30 April 2007 and has a priority date of 17 February 2007. It deals with a known problem. In earlier "pump in a box" products the pump and electronics were sealed together, so a leaking pump could flood the box and reach the live circuitry. Claim 1 describes a housing with a first chamber containing the pump, a separate water-tightly sealable second chamber for the control circuitry, and a removable non-watertight housing cover. DLP sued Coram UK Holding Limited in the Intellectual Property Enterprise Court, alleging that its Premium Pump and Bluetooth Pump infringed. Both pumps are made by a company referred to as Whale. In each product the pump and transformer are mounted on a flat plastic backplate fixed to the wall, and a cover is optional. The Premium Cover is screwed to the wall separately and does not touch the backplate; the Bluetooth Cover slots onto the backplate. By trial, DLP relied on claim 1 as granted and on claims 1 and 7 as it proposed to amend them. Coram counterclaimed that the patent was invalid for lack of novelty and for obviousness over three pieces of prior art: Grumbach, a German patent application; Gontar, a UK patent application; and Quantum, a commercial product. Coram dropped the novelty attack towards the close of the trial and opposed the amendments as adding matter. At the two-day trial on liability only, each side attacked the other's expert. Coram also relied on evidence from Whale to challenge the independence of DLP's expert, Mr Vare.