Microsoft yesterday overturned a $1.5bn ruling made against it for patent infringement.

Back in January a jury ruled that Microsoft had infringed two patents owned by Alcatel-Lucent relating to MP3 standards. It made the record award of $1.5bn.

Lucent was seeking further damages because the award only covered the period up to late 2005.

The case involved Microsoft's use of two patents relating to MP3 music formats.

Judge Brewster ruled that one of the patents was not in fact infringed by Microsoft and that ownership of the second patent was questionable. Therefore he overturned the jury's award of $1.5bn damages.

Alcatel told the Register that it plans to appeal the decision within the next 30 days.

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