A key Apple patent that the company successfully used against Samsung in its patent infringement courtroom brawl has been invalidated by the U.S. Patent and Trademark Office, reports "CNET."

All 20 claims of U.S. patent No. 7,844,915 -- also known as the "pinch to zoom" patent -- have been invalidated by the Patent Office today, following a re-examination. Samsung pointed this out in a filing to U.S. District Court Judge Lucy Koh this afternoon, noting that it was "relevant" given the company's effort for a retrial, as well as Apple's attempt at an injunction against a number of Samsung devices for infringing on this very patent, notes "CNET."

This is all part of the ongoing, global legal battle. Apple and Samsung have filed more than 30 lawsuits against each other across four continents. For example, Apple alleges that Samsung copied the slide-to-unlock technology of its iPhone and iPad devices. Read more at http://news.cnet.com/8301-13579_3-57560112-37/uspto-invalidates-key-appl... .