The Intellectual Property High Court on Friday overturned a lower court ruling and ruled that Justsystem Corp. can continue to produce and sell its Ichitaro word-processing software and Hanako graphics software because they do not infringe on a Matsushita Electric Industrial Co. patent.

The high court said Justsystem's Help Mode button in the Ichitaro and Hanako software does not have the same function as the icon in Matsushita's patent specifications.

Presiding Judge Katsumi Shinohara said the patent, filed by Matsushita in 1989 and registered in 1998, is "invalid because it lacks inventive elements."

He also said the icon "could have been developed with the technology before the application."

It is the first case in which the IP High Court has called its Grand Panel, comprising five judges, to make a decision.

The dispute centered on the help function that offers explanations on various function buttons in Ichitaro -- the biggest domestic rival to Microsoft Word -- and Hanako.

Users read the explanations by clicking on the Help Mode button.

Matsushita, which makes Panasonic-brand products, filed a lawsuit against Justsystem in August 2004, claiming the buttons in Justsystem's software violate an icon patent it holds.

On Feb. 1, the Tokyo District Court ruled in favor of Matsushita.

Justsystem, established in Tokushima Prefecture in 1979, appealed the ruling on Feb. 8.

"It was fair and appropriate that our claims have been approved," Justsystem said in a statement after the high court's decision.

Matsushita has not yet decided whether to appeal.