Microsoft could be spared making costly changes to its widely used web browser Internet Explorer as a dispute over technology is overturned.
Explorer could be staying the same
Last year an Illinois court ordered Microsoft to pay out $521 million to private firm Eolas Technology for an alleged infringement of technology.
Now the US Patent Office has invalidated the claim by Eolas.
Experts had worried that the changes required would damage the usability of the web.
Microsoft had begun to make changes but the work was suspended last month pending the US Patent Office review.
If upheld, the decision would also spare the software giant paying out damages to Eolas.
The disputed code relates to the way Internet Explorer works with programmes such as QuickTime and Flash media players. US Patent 5,838,906, granted in 1998, protects the execution of remote code embedded in hypertext pages.
At the time of the case there was widespread concern among internet experts that the changes required by Microsoft would damage the usability of the web for millions of users.
The case is not over as Eolas Technologies has 60 days to appeal. It remains hopeful that its claim on the web technology will be upheld.
Founder Dr Mike Doyle is a former director of the Academic Computer Centre at the University of California, San Francisco.
Since 1988 the US Patent and Trademark Office has only invalidated 151 patents out of nearly four million awarded.