A recent decision of the Patents Court [1] has highlighted how patent disputes can impact customers of a manufacturer and/or supplier who is allegedly infringing the patent.

The patent in suit concerned a "method of operating a wind power station" which the patent owner, Wobben, claimed was infringed by the manufacture and supply of competing technology by Siemens. Wobben maintained that Siemens was manufacturing, marketing and supplying wind turbines which incorporated technology that was the subject of the patent.

The other defendants were customers of Siemens and Wobben's claim against them was that they had used the wind turbines manufactured by Siemens in their wind farms. The companies that had installed the wind turbines for them were also added as defendants.

Wobben had also, earlier in the proceedings, obtained a Norwich Pharmacal order obliging Siemens to provide details of the identity of its customers within the jurisdiction of the court where the technology had been activated, or was to be activated between the date of the hearing and the trial.

Siemens argued that the patent was invalid. Having considered the prior art, the Court considered that the patent in suit was novel but that it lacked inventive step.  It considered that the approach taken by Siemens with respect to its own technology was obvious.

The Court went on to find that, even if the patent were valid, it had not been infringed. 

The decision was a technical one arrived at after a detailed analysis of expert evidence and the relevant technology. More generally, the interesting aspect of the case is Wobben's insistence upon joining in customers of Siemens as defendants, and also those responsible for installing the technology, and forcing the disclosure of the identify of customers who had purchased technology from Siemens. The customers in question would be unlikely to thank Siemens for being dragged into a dispute that they would think did not concern them and this could be a useful tactical weapon in patent disputes.