At issue is whether Microsoft violated its contract with Sun for developing and deploying products using the Java programming language and also Sun's Java copyright.
Microsoft's battle with Sun coincides with the software maker's ongoing antitrust battle with the federal government.
The hearing was to deliver oral arguments concerning Sun's request that the judge reinstate a preliminary injunction against Microsoft in a manner consistent with instructions from the U.S. Court of Appeals.
After the hearing, U.S. District Judge Ronald Whyte in San Jose, California did not indicate when he would issue a ruling.
Java, touted for its portability, lets software developers create programs that will run on virtually any operating system, such as Windows or Unix. Conformity is a big issue, argues Sun, if Java is to be ubiquitous.
Microsoft spokesman Jim Cullinan said the software giant told the judge there's no basis for Sun's request to reinstate the injunction or expand the injunction. "We said it was instructive to look at what the appeals court had to say," Cullinan said, after today's hearing. "Sun's trying to get the court to keep us from innovating and stop us from offering developers the tools they want."
In a prepared statement after today's hearing, a Sun spokeswoman said the company's attorneys argued that reinstatement of the injunction is necessary because Microsoft continues to violate its contract for using Java. "Sun demonstrated that without the injunction Microsoft's conduct is likely to recur, and, indeed, has already recurred," the statement said.
Sun alleges Microsoft made changes to Java's software code in violation of its copyright and the licensing agreement for using Java. Microsoft contends it is not trying to "highjack Java" as Sun alleges, but to make it work better with Windows.
Microsoft contends the dispute is contractual and not an issue of copyright, so it does not warrant the relief Sun demands.
Whyte issued a preliminary injunction in November 1998 ordering Microsoft to ensure its products using Java conformed to Sun's compatibility tests.
An appeals court in August overturned the preliminary injunction, delivering Sun an unexpected blow.
But the court of appeals also asked Whyte to clarify his ruling on the preliminary injunction, leaving open its possible reinstatement.
In a brief filed on September 23, Microsoft asked the judge to deal with both issues of copyright and preliminary injunction simultaneously and rule against copyright infringement.
The Sun case comes as Microsoft awaits the outcome of a much larger case, its antitrust battle with the federal government. The U.S. Justice Department and 19 states allege Microsoft used the dominance of Windows to crush Web browser rival Netscape Communications, now part of America Online.
In another matter, the Washington Post reported today Microsoft has been lobbying Congress to cut the budget of the Justice Department's antitrust division by $9 million.