The Consumers for Computing Choice (CCC) and the Open Platform Working Group filed a motion last to intervene in the case on the grounds that the settlement would harm both consumers and software developers.
The motion follows a similar move two weeks ago on the part of two other groups, The Computer & Communications Industry Association (CCIA) and the Software and Information Industry Association (SIIA), and an appeal of the settlement by Massachusetts and West Virginia.
The CCC and the Open Platform Working Group are seeking the right to appeal the settlement under the Tunney Act, which stipulates that before entering any final antitrust judgment, courts must consider the competitive impact of the judgment, the effect on the public generally and on individuals alleging specific injury from the antitrust complaint.
James Turner, a consumer interest lawyer who heads the CCC, said the settlement between Microsoft, the US Department of Justice (DOJ) and nine states that sued the software maker injures both software consumers and software developers by not going far enough to open Microsoft product source code to outside developers and to encourage innovation.
"Our basic argument is that we need to have interoperability for the 70,000 applications that Microsoft has. People have to be able to write programs to them," Turner said.
Nobody from the Open Platform Working Group could be reached for comment.
Turner added that Microsoft's dominance of the computer software industry is similar to the Bell system's dominance of the US telecommunications industry in the 1980s, where innovation is throttled by trying to control new technologies and use them to maximise profits rather than opening those technologies to unfettered development and competition.
The antitrust settlement, which was approved in November by US District Court Judge Colleen Kollar-Kotelly, prohibits Microsoft from retaliating against computer makers or independent software makers that consider developing, distributing, promoting, using, selling or licensing any software that competes with Microsoft platform software or any product or service that distributes or promotes any non-Microsoft middleware.
Microsoft's middleware products include Internet Explorer, Windows Media Player and Windows Messenger, as well as Outlook Express and its Java virtual machine.
Turner said middleware does not, in itself, address the overall competitive problem posed by Microsoft's dominance of the software industry.
"Microsoft has a toll bridge on the information superhighway and we want it to be a public road," Turner said. "We're happy with Microsoft putting vehicles on the road, but we're not happy when they say that only their vehicles can pass on the toll road that they own."
Turner claimed Judge Kollar-Kotelly latched on to the issue of middleware while ignoring other ways Microsoft uses its operating system monopoly to stifle development of software applications using competing systems.
While the CCC acknowledged it did not have the same right to intervene in the case as a Microsoft competitor, the group is asking Judge Kollar-Kotelly to use her discretion and the guidance of the Tunney Act to allow the CCC into the case to file an appeal.
If that failed, Turner said the CCC would turn to the US Court of Appeals to consider the request to intervene.