The US federal Court of Appeals has ruled that Koito Manufacturing Company of Japan, and its US subsidiary, North American Lighting Company, acted properly in the development and manufacturing of a key lighting component fitted to more than 30 different Japanese cars sold in the US.

The unanimous decision, which was returned by a three-judge panel this week, upheld an April 2003 jury verdict in the same case. The court found that the manufacturing process Koito used to mould plastic tail light lenses in no way infringed on a patent for another process that was held by Turn-Key-Tech.

The Federal Circuit sent the issue of whether Turn-Key-Tech's patent is valid in view of prior art back to the District Court for further review and consideration.

Multiple cases filed by Turn-Key-Tech against Toyota, Honda, Nissan, and other Japanese and Korean automobile manufacturers that focus on the same claims are pending.