The news: Google’s ad tech remedies trial kicked off Monday as the search giant looks to prevent an ad tech breakup that would fundamentally alter the future of the open internet.

The antitrust trial stems from a spring ruling in favor of the Department of Justice, which found that Google unlawfully maintains monopolies in open web display publisher ad exchanges and server markets by tying its ad server and ad exchange tools together.

What’s at stake: The DOJ and a group of US states aim to break up Google’s dominance by requiring it to sell its AdX exchange. The group also wants Google to make the system it uses to determine auction winners open source, as AdX currently charges publishers a 20% fee on ad sales.

The DOJ is not requesting Google to divest its DoubleClick for Publishers (DFP) ad server as part of the remedy. Given how intertwined the tools currently are, selling AdX would still fundamentally alter Google’s ad server and could strip the company of its ad tech dominance.

If the system is not forced to go open source, the DOJ is requesting the decision be revisited in two years, which would then include a potential total divestment of AdX. Similarly, if the DOJ’s remedies do not enhance competition in four years, Google is being requested to sell its publisher ad server.