When Canadian telecom Nortel went bankrupt in 2009, there was a bidding war between Google and a consortium called Rockstar Bidco for more than 6,000 Nortel patents. Rockstar, which is owned by Microsoft, Apple, RIM, Ericsson, and Sony, won the auction for $4.5 billion.

This afternoon, Rockstar filed suit against Google for patent infringement. You can read the complaint here.

From the complaint:

On August 1, 2000, United States Patent No. 6,098,065 (the “‘065 patent”) was duly and legally issued for an invention entitled “Associative Search Engine.” Rockstar is the assignee of the ‘065 patent and has granted an exclusive license to NetStar, who holds all rights and interest in the ‘065 patent. A true and correct copy of the ‘065 patent is attached hereto as Exhibit A.

Google has infringed and continues to infringe the ‘065 patent by its manufacture, use, sale, importation, and/or offer for sale of systems, methods, products, and processes for matching search terms with relevant advertising and/or information based on those search terms and other user data, including but not limited to Google’s process of receiving search requests from a user, using its search engine to generate search results based at least in part on the search request, selecting—through Google’s AdWords and/or any other products, methods, systems, or services Google uses to store and choose relevant advertising—a relevant advertisement based on the search request and/or user data, and providing the search results together with the particular advertisement to the user; and additionally Google’s systems, methods, products, and processes of using other user data aside from the search request to help select the search result and/or advertisement; and additionally and alternatively its contributing to and inducement of others to manufacture, use, sell, import, and/or offer for sale infringing systems, methods, products, and processes in the manners described above. Google is liable for its infringement of the ‘065 patent pursuant to 35 U.S.C. § 271.

This is going to get messy.