The trial is the governments next best shot at curbing what a judge has ruled is Googles monopoly power, after losing a separate bid to make Google sell its Chrome browser earlier this month. Online publishers and rival ad tech developers, some of whom have separately sued Google for damages, will be watching the case closely.
The US department of justice and a coalition of states are trying to make Google sell its ad exchange, AdX, where online publishers pay Google a 20 fee to sell ads in auctions that happen instantly when users load websites. The government is also seeking to require Google to make the mechanism that decides the winner of those auctions open source.
Julia Tarver Wood, an attorney with the justice departments antitrust division, said in her opening statement that making Google sell AdX was necessary to restore competition after US district judge Leonie Brinkemas ruling that the company illegally tied AdX to its publisher ad server a platform used by websites to store and manage their digital ad inventory.