Attorneys for Microsoft Corp. said  the computer expert who said he  found evidence that the company  is violating a federal ruling has been  proven incorrect.

The alleged misconduct surrounds  Microsoft’s duty to share software  hooks, known as application programming  interfaces, or APIs, which let different programs work together. The plaintiffs’ attorneys in the $330 million class-action antitrust lawsuit against the company have alleged that Microsoft has not disclosed certain APIs to other software developers  who want to make programs compatible with Microsoft software.

The expert, Andrew Schulman, reportedly found evidence that Microsoft wasn’t disclosing the APIs while digging through mountains of secret computer code that is used to make the software giant’s products.

During deposition by defense attorneys, Schulman said he found APIs that were not disclosed but made no judgement on whether they constituted a violation of the federal consent decree.

“I have not offered such an opinion,” he said in the deposition. “I believe, as is clear from our discussion here, that that involves interpretation of legal documents, which is not now within my field of expertise.”

Steve Holley, a lead counsel for Microsoft, said Schulman admitted he had not read several portions of the consent decree, portions that laid out what APIs the company had to disclose.

“The notion that we were in violation  of the federal decree was implausible  from the outset,” said Steve Holley, a lead counsel for Microsoft, adding:  “It’s frankly amazing that he accused  Microsoft of something without having  looked at the legal documents necessary  to make that accusation.”

Rick Hagstrom,co-lead counsel for the  plaintiffs, said this is just another public relations stunt the defense is using to distract people from the real issues.

“They set up a straw man, and then  they knock it down,” he said. “It’s the  same tactic they’ve been using throughout  the entire trial.”

Schulman never made an allegation that Microsoft was in violation of the federal decree, Hagstrom said. He simply said he had discovered undisclosed APIs and that the evidence should be turned over to the U.S. Department of Justice to make a  determination of whether Microsoft was in violation.

“He never rendered an opinion,” he said. “Microsoft is very good at this game of diversion.”

The original lawsuit against Microsoft by the Clinton-era Justice Department alleged that the company unlawfully used its monopoly in operating systems to block competition. After a lengthy battle that  included one judge’s recommendation  that Microsoft be split in two, the  Bush administration settled the case  with the agreement requiring Microsoft to share information with other software developers and go before a federal judge four times a year to ensure it is complying with all aspects of the consent decree. The latest hearing was in early December, and the court found no wrongdoing.

The API issue also has landed Microsoft into trouble with the European Commission, which imposed a fine of 3 million euros per day last July for failure to provide proper software documentation. In response, the company provided 8,500 pages of documentation in November.

This week, the plaintiffs will be calling  the first of their economic experts to testify.

Roger Noll, an economics professor at Stanford University, is expected to begin testimony today or tomorrow. Hagstrom said Noll will lay out for the jury the ways in which Microsoft has violated antitrust laws.

“He will make it quite clear for the jury that Microsoft’s course of conduct over the past 18 to 20 years has been anti-competitive,” he said. “They used  certain techniques to destroy competition  which led to an overcharge for their customers.”

For the nine weeks the trial has been under way, the plaintiffs have spent the majority of their time focusing on the history of Microsoft’s relationship with DR-DOS, a rival operating system that was prevalent in the late 80s and early 90s. Hagstrom said now that the jury understands what Microsoft did during those years, Noll can explain how the acts were anticompetitive.

Rich Wallis, associate general counsel for Microsoft, said the plaintiffs have spent nearly all of their time discussing things that happened many years ago, before the class period of this case.

“The issues they are bringing up have already been settled,” he said. “There may have been a mention or two of something that happened in the class period, but the rest is ancient history.”

Noll is expected to testify for four days