The US Department of Justice has launched a formal investigation among antitrust concerns about the settlement Google made with a number of authors and book publishing companies. The $125 million deal would allow the search giant to scan any book and become the exclusive provider of digital copies of the out-of-print ones.

"The United States has reviewed public comments expressing concern that aspects of the settlement agreement may violate the Sherman Act," wrote William F. Cavanaugh, the Justice Department's deputy assistant attorney general, in a letter addressed to the judge presiding the Google settlement, Federal District Court Judge Denny Chin. In response, the latter set a date for September 18 for the DOJ to present its case, three weeks before a scheduled hearing on the issue.

Google has confirmed it has been informed of the move by the DOJ and says it is cooperating with the institution. "The Department of Justice and several state attorneys general have contacted us to learn more about the impact of the settlement, and we are happy to answer their questions," Google Spokesman Gabriel Stricker said. "It’s important to note that this agreement is non-exclusive and if approved by the court, stands to expand access to millions of books in the U.S."

Google entered a settlement deal with book publishers and authors late last year over its Google Book Search project. Under the deal, the Mountain View-based company would create an easy way for copyright holders to claim their works and receive a cut of the profits from selling their books in ebook form. However, it also allows the company to sell any so-called “orphan book,” one for which a copyright holder doesn't step up or can't be found otherwise. This would make Google the sole provider of those books, something that the competition, and now the DOJ, isn't too happy about.