An appeals court in the United States has ordered a retrial of a court case that would have cost software giant Microsoft US$521 million had the appeal been unsuccessful. Microsoft was initially sued for patent infringement.

The University of California and Eolas Technologies filed the initial suit, claiming Microsoft had infringed on patents with the web browser, Internet Explorer. A lesser court had found Microsoft guilty and ordered the fine.

However, the appeals court has reversed part of the initial judgment, which allows Microsoft to re-state its case.