A US court has decided that Rockwell Automation has not infringed the PLC patent known as `318, owned by a company called Solaia Technology. For several years, Solaia has been extracting "licence fees" from large automation customers for using equipment which it claimed infringed the patent. Most of the customers paid the fees of up to $600,000, rather than risk costly court battles.

The legitimacy of Solaia`s claims had never been tested in court until Rockwell and the automotive parts supplier ArvinMeritor brought a case against Solaia.

Now a judge in Illinois has ruled that Rockwell and ArvinMeritor did not infringe the patent, which Solaia bought from Schneider Electric (which had inherited the patent when it bought Square D). Judge Mark Filip also denied a Solaia motion for a summary judgement against Rockwell and ArvinMeritor for allegedly infringing the patent.

In 2004, one of Solaia`s lawyer said that the company had already been paid more than $24m in licencing fees from around 60 US automation users. It is not clear whether these users will be entitled to claim their "fees" back. It is also unknown whether Solaia will appeal against the court decisions, or whether GE Fanuc Automation, which recently reached a settlement agreement with Solaia to protect its customers from having to pay the licence fees, will have any claims against Solaia.