More of the wind turbine at issue - MHI's flagship 2.4MW machine - are being installed in the US while the row proceeds, with the rest of the industry closely watching because of the wide applicability of three of the disputed patents.
Last month, a Texas jury found that Japan-based MHI and one of its affiliates infringed GE's '705 patent for zero-voltage ride-through technology (ZVRT), which allows turbines to cope with grid voltage fluctuations. The jurors, in a district court in Dallas, awarded GE $166.8 million for lost profits and $3.4 million for lost royalties.
Earlier in March, the US Court of Appeals in Washington DC had ordered the International Trade Commission (ITC) to review whether MHI violated GE's '985 patent for low-voltage ride-through (LVRT) technology.
"I think GE is winning at this point," said Eric Lane, an intellectual property (IP) lawyer and founder of Green Patent Blog. "It's the first to get an infringement verdict."
The '985 ruling is significant, added Philip Totaro of Totaro & Associates, an innovation strategist. "If the validity of '985 is upheld, it doesn't necessarily mean Mitsubishi is infringing, but nobody infringes an invalid patent," he said. The ITC had previously found the patent unenforceable because GE was not using it in the US.
Talking about the case, a spokeswoman for Mitsubishi Power Systems Americas, said: "It is premature for Mitsubishi to file an appeal." She noted that in a second phase of the trial in a few months' time, MHI is accusing GE of "inequitable conduct" in front of the US Patent Trademark Office, where a re-examination of the patent is expected to wrap up later this year.
It is often difficult to prove intent in inequitable conduct, said Lane. In response, Mitsubishi's Williams said: "There is an intent requirement in every fraud case, and fraud is successfully proved in court every day." GE denies the charge.
In the five IP lawsuits filed by GE and MHI, several other patents have been cited including GE's powerful '039 for variable speed. Although '039 expired in early 2011, GE could still collect damages for past infringement. The disputed patents with wide applicability are GE's '985, '039, and '705, noted Totaro. If any are invalidated, existing licensees could conceivably recoup licence fees already paid. Should their validity be upheld, there would be implications for market entrants such as Asian wind companies that have yet to gauge their IP risk or obtain licenses in America, he said.
MHI's 2.4MW turbine has been selected or installed at three US wind projects since the dispute began: at Edison Mission's 55MW Pinnacle project near the Maryland-West Virginia border; Duke Energy's Los Vientos II 202MW project in Texas, and for part of the 298MW Canadian Hills project developed in Oklahoma by Apex Wind Energy.