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Wobben Properties GMBH v Siemens PLC & Others

Case Summary  |  Judgment  |  19 January 2017


James Whyte represented the Respondents (collectively “Siemens”) in this appeal concerning Wobben’s patent for a method of operation of a wind turbine in high winds.

At first instance Birss J had found that Wobben’s patent was obvious in light of a prior art research paper “Bossanyi”, which disclosed strategies to mitigate the effects of wind turbine shut-down at high wind-speeds. The judge further held that, had the patent been valid, it would not have been infringed by Siemens’ turbines.

Wobben appealed on the basis that the judge had made fundamental errors of principle in his assessment of obviousness and that, in making his finding of non-infringement, the judge had made an error of construction in relation to how Siemens’ rotors responded to changes in wind speed.

The Court upheld the judge’s findings and dismissed the appeal. On obviousness, the Court held that the judge had been entitled to find that the system for controlling rotor speed in high winds described in the patent would have been obvious to the skilled person in light of Bossanyi, despite the fact that Bossanyi was primarily directed to fixed speed rotors, rather than the variable speed, variable pitch (VSVP) rotors that were the subject of the patent. The judge’s findings on how the skilled person would have applied Bossanyi to VSVP rotors were supported by the evidence.

Further, there was no basis on which to interfere with the judge’s finding that Siemens’ rotors would not have infringed the patent had it been valid.