In a Washington news conference, the chief executives of America Online, Compuserve and Prodigy released copies of a one-page letter they sent to Microsoft Chairman Bill Gates criticizing the arrangement, and said they would also appeal to congressional leaders to support a Justice Department investigation of the software giant’s proposed on-line service.

When it comes to the on-line business, we are not going to stand by while Microsoft engages in practices that jeopardize what is now an open, competitive and growing industry, said Compuserve President Bob Massey in a statement issued before the news conference.

The news conference comes as Microsoft prepares to go before a federal court judge Monday to argue that the Justice Department’s recent request for additional information on Microsoft’s new on-line network be turned down.

Advertisement

For months, the Justice Department has been investigating whether Microsoft’s bundling of an on-line service with it new Windows 95 computer operating software violates federal antitrust laws.

But the department’s probe has reportedly been proceeding cautiously out of concern that there may not be sufficient legal precedent to force Microsoft to unbundle the network from Windows 95.

Even lawyers for the on-line ser-

vices concede the difficulty of assembling an antitrust case because the technology is new and the Microsoft Network does not yet have a single paying customer.

It is generally illegal for someone with market power to tie a second product to the first one like Microsoft is attempting to do by bundling access to their on-line service in the operating system, said Donald I. Baker, a Washington antitrust lawyer, retained by Compuserve.

But antitrust cases turn very heavily on specific facts. Here, there are a lot of unknowns this is a very unusual case.

Although Microsoft general counsel William Neukom and other company officials had previously maintained Microsoft was making contingency plans to sever the network from Windows 95 if necessary, the software giant now says there is no turning back.

Advertisement*

There are no actionable antitrust issues that arise from the fact that we intend to include, with Windows 95, the access code to the Microsoft Network, said Neukom.