Sun has asking the Baltimore court for a preliminary injunction to keep Microsoft from distributing the Java technology it ships with Windows and force it instead to ship a Sun-authorised version with the operating system and the Internet Explorer Web browser.
The company has argued that Microsoft is scuttling the success of Java by shipping outdated technology with its products.
Java is a programming language developed by Sun and widely used by developers to build applications that can run on various operating systems and computing devices ranging from mobile phones to large servers.
US district judge Frederick Motz said he would attempt to make a decision on the preliminary injunction within the next 10 days, although Sun and Microsoft representatives warned it could take longer.
The hearing on Sun's request for a preliminary injunction included testimony from company executives, industry experts and economists representing both parties.
Sun charged that Microsoft used its desktop operating system monopoly to hinder Java's success. Microsoft uses older versions of Java technology in its products and has said it will stop shipping Java altogether in future releases of Windows. Users then would have to download a Java virtual machine themselves.
Sun called on executives and University of Chicago economist Dennis Carlton to testify earlier this week. Carlton suggested that forcing Microsoft to use Sun's Java technology would ensure competition in the emerging Web services development market. Microsoft has been developing its own Web services technology based on its .net initiative, which has emerged as the top competitor to Java.
Microsoft lawyers have attempted to prove that any failure of Java is Sun's own doing.
Microsoft also is relying on the federal antitrust suit against Microsoft settled earlier this year, where US District Court Judge Colleen Kollar-Kotelly rejected a similar request to force Microsoft to ship its products with Sun-backed Java support on grounds that it would not be a benefit for competition.
"This remedy is unwarranted, it would be unprecedented and is unsupported by the law," said Jim Desler, Microsoft's legal spokesman yesterday. "The burden was on Sun to provide evidence, and we don't believe they provided the necessary evidence."
Sun is also seeking a broader set of remedies as part of its private antitrust suit, which is still getting under way. It has asked for monetary damages and a permanent injunction that would require Microsoft to license to other companies certain proprietary software interfaces. It would also require Microsoft to "unbundle" products from its operating system, such as Internet Explorer and the IIS (Internet Information Server) Web server.
Giga research director Rob Enderle cautioned yesterday that Sun might be overreaching in its legal pursuit. He cited comments Motz made during hearings on Wednesday, in which the judge said Sun might be better off focusing its efforts on Java and abandoning its other demands.
"If you over-ask you really run the risk that the judge is going to consider you unreasonable," Enderle said.
Sun brought its antitrust suit against Microsoft in March. The case was transferred to Baltimore under Motz along with separate private antitrust suits filed by AOL Time Warner's Netscape division, as well as the former operating system maker Be and software vendor Burst.com.
All those cases have been consolidated under Motz, in addition to a collection of class-action lawsuits filed by consumer plaintiffs against Microsoft.