Google has reportedly been questioned by the U.S. Justice Department over whether their plan to digitize the world’s books into an online database represents a potential antitrust violation, according to the New York Times.

A recent settlement guarantees Google equal terms as any competitor, such as Microsoft, in any future negotiations over digital book rights.

The questioning of Google, the Author’s Guild and the Association of American Publishers, however, does not necessarily mean that the Justice Department will attempt to prevent the deal over antitrust issues.

Authors who accept the settlement terms will give Google permission to scan their works digitally to appear in its search index, and share in any revenue generated by the search engine giant.

Google has declined to comment about the reported Justice Department review. But in a post on its public policy blog on Wednesday, Adam Smith, director of product management for Google Book Search, defended the project as a way to expand access to out-of-print books and as a potential source of revenue for authors and publishers.