Google owned Motorola Mobility has been ordered to pay Microsoft around $14.5 million (£9.3 million) in damages by a US judge after the company was found to be licensing its patents at an unreasonable rate.
A federal jury ruled that Google and Motorola Mobility did not act in good faith when it demanded patent royalties from Microsoft for video-compression and Wi-Fi technology used in products such as the Xbox.
The figure is just half of the $29 million (£18.6 million) in damages that Microsoft sought, but the company remained happy with the outcome.
"The jury's verdict is the latest in a growing list of decisions by regulators and courts telling Google to stop abusing patents," David Howard, Microsoft deputy general counsel, said in an statement. "This is a landmark win for all who want products that are affordable and work well together."
Motorola Mobility has said it will appeal the decision. In a statement, company spokesperson William Moss said: "We're disappointed in this outcome, but look forward to an appeal of the new legal issues raised in this case."
Despite Microsoft's assertion that Google should "stop abusing patents", the ruling is in fact part of a long standing dispute between Microsoft and Motorola, which predates Google's acquisition of Motorola Mobility, with Microsoft first suing the company in 2010.
Google acquired the mobile phone arm of Motorola, which became known as Motorola Mobility after the company was split in 2011, following a collapse in profits.
The ruling follows an earlier Microsoft victory in which a judge ruled that the company should only pay Motorola Mobility $1.8 million (£1.15 million) a year in royalties relating to patents, after Motorola had asked for billions.