WASHINGTON (AP) — The Supreme Court has declined to take up software maker Novell Inc.'s appeal in a long-running antitrust case against Microsoft Corp.

The justices on Monday let stand an appeals court ruling that rejected Novell's $1 billion lawsuit alleging Microsoft undermined the once popular WordPerfect writing program in favor of its own Word program with the Windows 95 rollout.

Novell claimed Microsoft duped it into developing WordPerfect for Windows 95 only to pull the plug so Microsoft could gain market share with its own product. Novell says it was forced to sell WordPerfect for a $1.2 billion loss.

The 10th Circuit ruled that Novell's complaint came too late and it failed to make the larger case that Microsoft was protecting a monopoly on operating systems.