Telecom giant Nortel went bankrupt in 2009 and auctioned off its patent portfolio. Though Google tried to acquire it, ultimately the bidding escalated to a point where the winner turned out to be a consortium of tech giants, currently operating as Rockstar. The companies involved in purchasing the patents from Nortel are Microsoft, Apple, RIM, Ericsson and Sony. At the end of October, Rockstar filed suits against Google and seven manufacturers of Android phones, claiming they had infringed various patents.

Interestingly, Rockstar is using the fact that Google attempted to acquire Nortel's patent portfolio as evidence against the company.  "Google subsequently increased its bid multiple times, ultimately bidding as high as $4.4 billion," wrote Rockstar's lawyers, according to Ars Technica. "That price was insufficient to win the auction, as a group led by the current shareholders of Rockstar purchased the portfolio for $4.5 billion. Despite losing in its attempt to acquire the patents-in-suit at auction, Google has infringed and continues to infringe the patents-in-suit."

There are six patents Google is accused of infringing, all falling in the same category of claims to an "associative search engine" model that can deliver targeted ads to users making searches on a data network. The oldest patent in the family is from 1997, and the newest filed in 2007 and granted in 2011.