Huge fines followed in the wake of the 2004 ruling.
The European Commission is scaling back its scrutiny of Microsoft.
Regulators have ended full-time monitoring of Microsoft that was started to ensure the firm was complying with an anti-trust ruling.
The 2004 ruling forced Microsoft to share information about the internal workings of its software with rivals.
Brussels said the shift was driven by Microsoft's improved behaviour and legal changes that meant market abuse could be tackled at national level.
In March 2004, Microsoft was hit with a 497m euro (£441m) fine for abusing its dominant market position that stopped rivals prospering in the desktop and server software markets.
The ruling forced it to unbundle some of the products included in standard installations of Windows such as Media Player.
The 2004 decision also made Microsoft pass information about its operating systems to rivals so they could improve the way their programs worked with the software.
In 2005, Prof Neil Barrett was appointed as a full-time monitoring trustee to assess the information Microsoft had provided.
Microsoft appealed against and lost the court battle to overturn the fine and was then hit with another penalty of 899m euros (£798m) in February 2008 for defying the initial ruling.
In a statement, the Commission said it "no longer requires a full time monitoring trustee to assess Microsoft's compliance".
While it said monitoring was still "necessary" it said the information it needed could be found through other, more passive, means.
It added that the licences Microsoft has granted to third-parties to use the interoperability information could be challenged in national courts, also removing the need for full-time oversight by Brussels.
Other European anti-trust cases are ongoing. The Commission is still investigating whether Microsoft abused its position while bundling the Internet Explorer browser with Windows.
Microsoft said it was committed to ensuring it stayed compliant with European laws and would continue to cooperate with the Commission and its experts.