Microsoft has lost the latest round of its battle against sanctions in Europe.
Microsoft has been working hard to shake off monopoly allegations
A US judge quashed the firm's demands that rival Novell hand over documents it presented to the European Commission for use in an anti-trust case.
The judge in the case said he had turned down the request as Microsoft was trying to "circumvent and undermine" European law.
Microsoft is fighting a European Union (EU) ruling that could trigger fines of up to 2m euros ($2.4m; £1.4m) a day.
The latest ruling by Boston district court judge Mark Wolf comes a week before Microsoft faces the EU's second highest court to appeal against a 2004 ruling that it had abused its dominant market position.
'Ignoring the rules'
"Enforcing Microsoft's ... subpoena to Novell would circumvent and undermine the law of the European Community concerning how a litigant may obtain third-party documents," judge Wolf said in his 12-page decision.
Last month, the software giant asked US federal courts to force four of its rivals to hand over documents relating to the European case.
However, its attempts to subpoena sensitive information from Oracle and Sun Microsystems were turned down by a Californian judge last month.
A New York judge is currently considering a request against IBM.
Brussels has ordered Microsoft to provide rivals with the information needed to make their software work with Microsoft servers.
The European Commission has threatened Microsoft with daily fines if it was found to be dragging its heels over the issue.