Sun Microsystems and Microsoft were back in court Friday, where Sun urged the reinstatement of an injunction requiring Microsoft in its products to use a version of Java that passes Sun's compatibility tests.

Each side presented one-hour oral arguments to US District Court Judge Ronald Whyte, offering their interpretation of an August federal appeals court ruling that had suspended the injunction.

The appeals court had questioned Whyte's finding that Microsoft has likely infringed on Sun's Java copyright, and asked him to clarify the grounds on which he granted the injunction. At the same time, the appeals court said it was inclined to agree with Whyte that Microsoft had likely breached its Java licensing contract.

Whyte, of the US District Court in San Jose, California, gave no indication Friday when he would rule on whether or not to reinstate the injunction, spokespeople for the two companies said.

Sun's lawyers told the court Friday that Microsoft will continue to behave anti-competitively if the preliminary injunction is not reinstated, and cited recent examples of Microsoft's alleged false advertising and failure to update prior Java products to keep them in line with Sun's Java compatibility test suites, Sun said in a statement issued late Friday.

Microsoft's lawyers, meanwhile, accused Sun of trying to broaden the scope of the preliminary injunction in a manner that is anti-competitive. Microsoft told the court that Sun is trying to prevent companies like Microsoft from making Java products that compete with its own, according to Microsoft spokesman Jim Cullinan.

Microsoft also urged Whyte to interpret the appeals court ruling in its favour.

"We believe the appeals court is saying that Sun can't have it both ways, by saying that this is both a copyright infringement issue and a breach of contract," Cullinan said.

Sun and Microsoft have been doing battle since November 1997, when Sun filed a lawsuit charging Microsoft with breech of contract, copyright infringement and anti-competitive behaviour for allegedly using an "impure" version of Sun's Java programming language in some of its software products.

Java can be used to write applications that run on any operating system, and Sun has argued that Microsoft saw that cross-platform capability as a threat to Windows. Sun argues that Microsoft countered the threat by illegally promoting a version of Java that is tied to features in Windows.

Judge Whyte's November 1998 injunction required Microsoft to bring its software products that use Java into line with Sun's version for the duration of the case. The affected products included Windows 98, Internet Explorer and a handful of development tools.

Acting on an appeal of that decision from Microsoft, the Ninth Circuit Court of Appeals in August said Judge Whyte had erred by granting the injunction based on a likelihood that Microsoft infringed on Sun's copyrights. Microsoft has argued that the case is a contract dispute.

No trial date for the case has been set.