The Department of Justice is taking its antitrust battle with Google to the next level — unveiling a sweeping, three-phase plan that could force the tech giant to break apart its powerful online advertising empire. The new remedy proposal, filed ahead of a high-stakes trial scheduled for September, aims to dismantle what the DOJ describes as an illegal monopoly over the digital ad marketplace.

At the heart of the plan is the government’s effort to unwind years of consolidation that have given Google near-total control over how ads are bought, sold, and served across the internet. Judge Leonie Brinkema already ruled in April that Google had unlawfully monopolized ad tech infrastructure. Now the court must decide what to do about it.

Phase one of the DOJ’s proposed remedy would force Google to share real-time AdX bidding data with rival ad exchanges through the Prebid system. That’s essentially opening up Google’s internal auction process — something advertisers and smaller platforms have demanded for years.

Phase two would require Google to open-source the “auction logic” behind its DFP (DoubleClick for Publishers) ad server. This would allow competitors to understand, and potentially replicate, how Google determines winners in its ad auctions — a black box system that critics say has long favored its own products.

The final and most explosive phase is full divestiture: the DOJ wants Google to sell off both AdX and DFP entirely. The companies would be placed in the hands of a court-appointed trustee until suitable buyers are approved. During that time, Google would be barred from operating an ad exchange — potentially for a decade. The government even wants Google to place 50% of all revenues from these divisions into escrow until the sale is complete.

These moves are a clear signal that the DOJ sees structural reform — not promises or policy tweaks — as the only path to restoring competition in online advertising.

“Behavioral remedies won’t work,” the DOJ argued, citing Google’s past abuse of regulatory settlements. Regulators say that without dismantling its dominant ad stack, Google will continue using its position to stifle innovation and disadvantage rivals.

Google, naturally, has a very different idea. The tech giant’s counter-proposal focuses mainly on softer reforms: sharing real-time data through Prebid, removing its “Unified Pricing Rules,” and committing not to restore its controversial “first-look” and “last-look” auction perks. Critics have already blasted the company’s suggestions as cosmetic, not structural — saying they do little to change the rigged nature of the ad market.

Google’s lawyers argue that spinning off AdX and DFP would be chaotic and unworkable, but Judge Brinkema appeared open to the idea at a recent hearing. That has given momentum to the DOJ’s more aggressive plan — and stirred anxiety in Silicon Valley and Wall Street.

The September 22 trial will be closely watched, not just because it’s the biggest antitrust showdown since the Microsoft case, but because it marks the first serious effort to break up a major tech platform since the rise of Big Tech.

Meanwhile, this isn’t the only courtroom battle Google is facing. In a separate antitrust case over its search engine dominance, regulators are threatening to force the company to spin off Chrome and halt billion-dollar payments to Apple and Android device makers. The result of that case could land just months after the ad tech ruling — and together, they could reshape Google’s entire business model.

What comes next is a months-long legal slugfest: factual discovery, expert testimony, reply briefs, and final arguments. But one thing is already clear — the government is no longer content with warnings. They want Google broken up, and for the first time in years, they might actually do it.