The legal standard of proof in the Microsoft antitrust case, as a civil action, is the court's judgment of which side is favoured by a 'preponderance of the evidence'. The mere phrasing suggests a carefully calibrated balancing - 51 to 49 is all it takes to win. But since so much of the case revolves around what happened at private meetings between Microsoft and other companies, the judicial balancing will lean heavily on credibility. The battle for the high ground on the credibility issue started on the first day of the trial, back in October, with the government's showing parts of the videotaped deposition testimony of Microsoft chairman Bill Gates. He came across as combative, evasive and forgetful. Put simply, he did not act or sound like Bill Gates. The government's message from the start has been what Microsoft says is not believable. It was not until last week that Microsoft's defence began in earnest, when the first of nine Microsoft executives took the stand. Starting with Paul Maritz, the most senior company executive to testify in person, US District Judge Thomas Penfield Jackson has begun hearing Microsoft's views. Judge Jackson, who alone will decide the outcome of the case (subsequent appeals are certain), must weigh the atmospherics and particulars surrounding each of the episodes in dispute. So the question becomes: whose revisionist history is more credible? To give a flavour of the task facing the judge, it is useful to take a closer look at two of the allegations in the case - that Microsoft tried to persuade Netscape Communications illegally to divide up the Internet browser market; and that Microsoft strong-armed Apple Computer into favouring Microsoft's browser over Netscape's. Both episodes came up last week in court, and will again. On June 21, 1995, a group of Microsoft executives met Netscape and, according to the government, offered a collusion deal, a violation of antitrust laws. The government has some incriminating evidence that includes meeting notes typed by Marc Andreessen of Netscape suggesting a 'threat' that Microsoft would take the browser market for its Windows 95 operating system and 'that Netscape should stay away'. Most facts about the meeting were known before the government filed suit last year, including Microsoft's proposal to buy a stake in Netscape, take a board seat and share information and plans. Netscape rejected the proposal. The Justice Department's interpretation of the June 1995 meeting as an invitation to collude was a new and damaging wrinkle. Still, there is some wiggle room on this for Microsoft. A four-page letter by Netscape's outside counsel in response to a subpoena from the Justice Department - a subpoena issued a day after the meeting - details the Microsoft proposals, including a threat to withhold technical information. But it does not mention an invitation to divide the browser market. In addition, James Barksdale, the president of Netscape, has said that the 'singular act' prompting him to complain personally to the Justice Department was Microsoft's threat to terminate the Windows licence of Compaq Computer if it did not bundle Microsoft's Internet Explorer browser with the operating system. That threat did not come until June 1996, a year after the Microsoft-Netscape meeting. Mr Barksdale, a key witness for the government, is not an antitrust expert, but his comment does raise questions about how incriminating the June 1995 meeting really was. In the Apple deal, the government alleged that Microsoft threatened to stop developing its Office Suite (word-processing, spreadsheet and database software) for the Macintosh unless Apple made Internet Explorer the preferred browser on Macintosh computers. Microsoft replied that the browser was a modest element in its August 1997 deal with Apple, which included an investment of US$150 million in Apple and an undisclosed payment (estimated at $100 million) to settle a patent dispute. Earlier in the trial, Microsoft claimed that a faltering Apple was then threatening to file a $1.2 billion patent suit. The patent issue, Microsoft insists now, was the primary focus of the 1997 deal. When the Apple deal was announced, the patent issue was not featured, so many have viewed that defence with scepticism. But Microsoft executives, including Mr Maritz, have tried to strengthen the patent argument. First, from a public relations standpoint, Microsoft said it wanted to emphasise positive elements of the deal instead of declaring that there was money to be made threatening Microsoft with patent infringement.