Twitter Inc., Facebook Inc. and Snap Inc., the developer of Snapchat, each knocked out a patent that’s part of a Xerox Corp. unit’s separate lawsuits accusing the social media companies of copying technology used to stop the spread of false news on their platforms.

In one of three decisions issued late Wednesday, the Patent Trial and Appeal Board ruled that none of the 20 claims in Palo Alto Research Center Inc.’s US Patent No. 9,208,439 should’ve been granted patent protection as the purported innovations would’ve been obvious to skilled engineers based on prior art.

In the other decisions …