Today, US District Judge Amit Mehta heard opening statements in the Department of Justice’s antitrust case challenging Google’s search dominance.

Mehta alone will decide if Google maintained its role as the world’s search leader by competing on its own merits—as Google has claimed—or through anticompetitive conduct—which the DOJ has alleged.

The DOJ’s head of antitrust, Jonathan Kanter, kicked off the proceedings. He told Mehta that the DOJ plans to establish that since 2007, Google has illegally maintained monopoly power in search and advertising markets by focusing on “weaponizing” the “power” of being the default search engine on mobile devices.