Microsoft’s appeal against a $290m patent infringement fine has been rejected by the US Supreme court.

In 2007, Canadian firms i4i sued Microsoft, saying Microsoft had integrated text manipulation technology for which it owned the patent into the Word population.

Microsoft was ordered to pay the fine for wilful breach of patient by all lower courts, and to stop selling infringing versions of Word.

Microsoft’s defence focused on the standard of proof of infringement in US patent cases, which it said was too high. Defendants in US patent cases must show that 70-80% of "clear and convincing" evidence supports their case, but Microsoft claimed they should only need to show that 50% was in their favour.

The Supreme Court ruled that the 70-80% standard was correct.