Around October 2007, Archive users began uploading public domain books from Google Book Search. , there were more than 900,000 Google-digitized books in the Archive's collection; the books are identical to the copies found on Google, except without the Google watermarks, and are available for unrestricted use and download. Brewster Kahle revealed in 2013 that this archival effort was coordinated by Aaron Swartz, who with a "bunch of friends" downloaded the public domain books from Google slow enough and from enough computers to stay within Google's restrictions. They did this to ensure public access to the public domain. The Archive ensured the items were attributed and linked back to Google, which never complained, while libraries "grumbled". According to Kahle, this is an example of Swartz's "genius" to work on what could give the most to the public good for millions of people. Besides books, the Archive offers free and anonymous public access to more than four million court opinions, legal briefs, or exhibits uploaded from the United States Federal Courts' PACER electronic document system via the RECAP web browser plugin. These documents had been kept behind a federal court paywall. On the Archive, they had been accessed by more than six million people by 2013.