The United States Patent and Trademark Office has dealt a blow to Apple in its legal battle with Samsung Electronics over smartphone patents, declaring that a patent that helped Apple win $1.05 billion in damages against Samsung in a jury trial should not have been granted.

The patent office’s action this week was made public by Samsung in a filing on Wednesday in Federal District Court in San Jose. In the court document, Samsung, the Korean electronics giant, said the action should be weighed in evaluating its petition for a new trial and its challenge to the damages award.

Apple is expected to appeal the patent office’s ruling, so the patent has not been invalidated yet.

The patent, No. 7,844,915, is one of six that a jury in August found that Samsung had infringed. It covers usability software that distinguishes between single-touch and multitouch gestures on a smartphone or tablet screen.

The patent is widely known as the “pinch to zoom” patent, but the software is actually narrower in scope. Apple’s legal documents refer to it as controlling a “scroll versus gesture” feature.