The US Supreme Court on Monday denied a request by Microsoft to halt an antitrust suit that Novell filed against the company for anticompetitive behaviour it said harmed its WordPerfect and QuattroPro business in the 1990s.

The Supreme Court denied a writ of certiorari request by Microsoft for a case Novell filed in a US District Court in Maryland nearly ten years after the company sold the programs in question to Corel. A writ of certiorari asks the Supreme Court to review and rule on a decision by a lower court and is typically filed by a losing party in a case.

In the ruling that denied the writ, posted on the Supreme Court website as part of the order list for Monday, chief justice John Roberts "took no part in the consideration or decision of this petition." According to published reports, Roberts abstained from ruling because he is a Microsoft shareholder.

In its original suit, Novell accused Microsoft of withholding technical information about Windows that would help its WordPerfect and Quattro Pro programs work with the OS and, as a result, the programs lost critical market share. Novell filed the suit shortly after Microsoft paid the company $536 million to settle antitrust claims over Novell's NetWare OS.

Microsoft said Novell's claims in the case were not valid because its productivity software did not compete with Windows. However, in June 2005, Maryland Judge J. Frederick Motz ruled that Novell's antitrust claims could go forward based on the 2002 federal antitrust case brought against Microsoft by the US Department of Justice. Both a federal district court and the 4th Circuit Court of Appeals upheld the Maryland court's decision.