Google violated U.S. antitrust laws in maintaining a monopoly over the online search business, a federal judge ruled Monday, in a landmark ruling for the Justice Department in its efforts to rein in big tech giants.

D.C. District judge Amit Mehta declared Google violated Section 2 of the Sherman Act, finding the company illegally secured its dominance in the search market by paying billions of dollars to smartphone carriers like Apple to make Google the automatic search engine for their phones -- effectively locking any rival businesses from being able to compete.

"Google is a monopolist, and it has acted as one to maintain its monopoly," Mehta wrote in his ruling.

This is a developing story. Please check back for updates.