Microsoft has filed a patent infringement case against satellite navigation gadget maker TomTom.
Microsoft said the legal action was taken after a year of negotiations with loss-making TomTom didn't result in a licensing agreement.
Horacio Gutierrez, Microsoft corporate vice president and deputy general counsel of intellectual property and licensing, said the firm had filed an action in the US District Court for the Western District of Washington and in the International Trade Commission (ITC) against TomTom NV and TomTom Inc.
TomTom is said to have infringed Microsoft patents in "car naigation technology and other computing functionality".
Gutierrez said, "We have an established intellectual property licensing program, and the patents involved in this case have been licensed by many others.
"In situations such as this, when a reasonable business agreement cannot be reached, we have no choice but to pursue legal action to protect our innovations and our partners who license them."
TomTom has just posted a fourth quarter loss, despite being one of the main players in the growing satellite navigation market.
TomTom has not commented on the Microsoft action.