The US Department of Justice (DOJ) has slammed Microsoft’s proposals for changes in its business practices in order to restore competition to the software industry, repeating its call for the software colossus to be split in two.

In its filing to the court, the DOJ claimed: "Microsoft's proposed remedy would leave it free to continue the very practices which the evidence at trial showed, and this Court found, to be unlawful and would do nothing to restore competition."

The remedy is intended to end Microsoft’s unlawful conduct and prevent it breaking the law in the future. The DOJ claims Microsoft’s proposals will do nothing to ensure these aims. The filing also suggests that Microsoft has shown no good reason why it should not be broken up.

Fact The DOJ said: "Microsoft attempts to elude the need for structural relief by pretending, contrary to the evidence at trial and this court’s findings of fact, that its conduct has had no effect on the competition." Trial evidence showed that Microsoft’s conduct eliminated the threat to its monopoly posed by Netscape and Sun.

The DOJ recommended that Microsoft be split into two separate firms last month – one focused on Windows OS, the other concentrated around software applications. The DOJ also recommended that restrictions be placed on Microsoft’s business practices, these include making key Windows application programming interfaces (APIs) available to independent software vendors (ISVs) to give them a better chance to compete with Microsoft.

Weak Last week, Microsoft suggested a set of much milder remedies, including placing limits on the way it deals with its Windows customers, and offering a version of its Windows operating system that hides the icon for Microsoft’s Internet Explorer.

The next stage in the case is for Judge Jackson to hear oral arguments about the differing remedy proposals on May 24. Microsoft has asked the Judge to delay the start of these until December 4, if he intends breaking the company up – Microsoft argued that it would need this time in order to prepare an adequate defence.

A copy of the DOJ filing is available from