Microsoft has lost a bid to have a European antitrust ruling reversed, and over £700 million in fines will stand.
That's slightly lower than the £868 million fine imposed back in 2008, however.
The General Court of the European Union found that penalties imposed on Microsoft years ago are valid.
The case dates back to 2004, when the EU fined Microsoft for refusing to license access to its technology on fair and reasonable terms, and ordered it to begin doing so. Four years later, the commission found that Microsoft had failed to comply with its order and fined Redmond the record sum.
Microsoft appealed and asked that the decision be annuled or reduced.
"In its judgment of today, the Court essentially upholds the Commission's decision and rejects all the arguments put forward by Microsoft in support of annulment," according to the court's decision.
The fine, however, was reduced slightly thanks to a deal that allowed Microsoft to restrict access to its technology until September 2007, when one aspect of the case was decided.
"Although the General Court slightly reduced the fine, we are disappointed with the Court's ruling," a Microsoft spokesman said. "The fine, which was paid several years ago, related to the price Microsoft had proposed for one of several forms of licenses for technology Microsoft was required to make available by the Commission's 2004 Decision. In 2009 Microsoft entered into a broad understanding with the Commission that resolved its competition law concerns."
In a statement, Joaquín Almunia, EU vice president, said he welcomed today's decision. "The ruling confirms that Microsoft did not comply with the Commission's decision and that the Commission was right to impose a penalty," he said.
"The requirement that Microsoft disclose information to its competitors so as to allow interoperability between the dominant Windows architecture and rival work group servers brought significant benefits to users," Almunia continued. "A range of innovative products that would otherwise not have seen the light of day were introduced on the market. The Commission's determination to enforce that requirement was instrumental in achieving that result."