Inventor Holdings’s campaign is growing steadily since the entity took on several cases from Walker Digital earlier this year. The Patent Properties subsidiary most recently sued Microsoft asserting a patent that it has used in only one previous case, against Google (8,558,921). In the complaint Microsoft’s photo gallery service is accused of infringing the asserted patent.The patent-in-suit relates to facilitating tagging people in photos by referencing a database of stored images, and was developed by Walker Digital. Inventor Holdings acquired the patent via assignment in November 2013 and first asserted it in litigation in February of this year. Walker Digital transferred the patent to Inventor Holdings as part of a group of 16 patents and Inventor Holdings was substituted as the plaintiff in two cases that involved patents transferred in that group. The entity has filed an additional four suits including this filing. 6/6, District of Delaware, 1:14cv00720