Discovery Patent Holdings filed suit against Amazon on July 14th, claiming Amazon's line of Kindle e-book readers infringe on two patents held by the company. "Amazon was originally sued by Discovery Communications in March 2009, accused of violation of a patent on e-book readers titled "Electronic Book Security and Copyright Protection System" (#7,298,851). This covered Kindle and Kindle 2 models. And the newest suit names Discovery Patent Holdings as the plaintiff and adds DX model as well as a new patent which was titled "Electronic Book Selection and Delivery System" (#5,986,690)."
Discovery holds rights to a third e-book related patent (#7,716,349) titled "Electronic book library/bookstore system," however that one applied for in 2000 and not issued until 2010 isn't part of the suit. The '690 patent was issued to Discovery Communications in 1999, while the '851 patent was awarded in 2007. According to court documents, the patents were transferred to Discovery Patent Holdings on July 12th 2010. It appears as if Discovery Patent was spun off to hold its parent company's intellectual property, and thus the suit was refiled.