The filings, submitted in the US District Court for the District of Columbia, come in response to a motion issued by the Computer & Communications Industry Association (CCIA) and the Software and Information Industry Association (SIIA) last month, seeking to intervene in the historic case.
In November, US District Court Judge Colleen Kollar-Kotelly approved the settlement of the antitrust case reached by Microsoft, the DOJ and nine of the suing states.
The CCIA and the SIIA have claimed that the government's settlement did not impose harsh enough remedies against Microsoft. They are seeking to intervene in the case under a law which stipulates that before entering any final antitrust judgment, courts must consider the competitive impact of the judgment, as well as the effect on the public, and individuals that have alleged injury from the antitrust complaint.
However, both the DOJ and Microsoft claimed the groups do not meet the legal requirements for intervention.
The opposition memoranda are part of a series of legal moves since the government settled with Microsoft.
Last week, two groups representing consumers and software developers also tried to intervene in the settlement.