Greens in the European Parliament are calling on the European Commission to ban Microsoft from bidding on future EU procurement contracts.
Their call comes after the firm was fined for its anti-competitive behaviour in 2004, and its failure to comply with the judgement since then.
Although the European Commission has so far not offered a straight yes or no response to the Greens' proposal, the Greens are pointing to the fact it has not ruled out a ban on Microsoft when it comes to future procurement.
Caroline Lucas, south east England Green MEP, said, "It is disappointing that the commission has refused to give clear guidance on the role that Microsoft can or cannot play in future procurement processes.
"Yet, although it gives no guarantees, there is a sense in which it does imply that the company's history of anti-competitive practices may be considered on a case-by-case basis."
In a written enquiry to the European Commission, green MEPs had asked whether Microsoft should be excluded from current or future public procurement procedures, citing Article 93 of the EU's Financial Regulations.
These regulations stipulate that bidders that are guilty of serious misconduct and have been convicted by the courts should be excluded from procurement procedures.
Lucas said, "Article 45 of the EU procurement directive (2) stipulates that companies which have legal judgments against them can be excluded from the award of public contracts - whether it concerns new software for a small town library or the setting up of a database for a whole regional office.
"Open source software should be made more widely available by EU institutions in order to help combat the destructive monopoly of Microsoft and to help reduce the 'digital divide'."