Samsung, which is battling Apple across the globe for dominance of the smartphone market, dealt the California company a setback by winning a preliminary invalidation of a key Apple patent, according to a court filing.
The fight is related to Apple's war against Google, whose Android software powers many of Samsung's devices.
Samsung said in a filing late on Monday (US time) that examiners at the US Patent and Trademark Office (PTO) had taken a second look at an Apple patent and decided that it should not have been granted. The patent allows a user with a touch screen to bounce back to the image on the screen if the user goes beyond the edge.
The patent was one of six that Samsung was found to have infringed by a jury in a California federal court in August. It awarded Apple $US1.05 billion in damages.
The case is being appealed, and Samsung is pursuing other challenges such as requests for the PTO to re-examine the patent.
Scott Daniels, a litigation partner at Westerman, Hattori, Daniels & Adrian who is not part of the case, said the PTO's preliminary invalidation is not the end of the battle over this specific patent.
He said the patent remains valid through the appeals process.