A decision by the United States District Court for the Western District of Wisconsin has reduced the scope of patent infringement litigation between global positioning system players Garmin Ltd. and TomTom.

According to a TomTom statement, Judge Barbara Crabb ruled that five Garmin patents were either invalid or not infringed by TomTom’s GPS products. Garmin countered that three patents held by TomTom were not infringed, according to the ruling, but multiple patent infringement claims asserted by Garmin against TomTom were left unresolved, and Garmin intends to pursue them.

Garmin said it owns 289 U.S. patents and 13 foreign patents and has 181 patent applications pending. Last August, Garmin filed suit against TomTom in the Eastern District of Texas alleging infringement of a single patent (#7062378) said to cover the core features of all portable navigation devices. That suit, which TomTom says is without merit, will go to trial in the fall of 2008.