In a pivotal remedies trial, the U.S. asks a federal judge to order a spin‑off of Google’s ad tech businesses—testing the limits of modern antitrust

ALEXANDRIA, Va. — The U.S. Justice Department and a coalition of states have asked a federal judge to order Alphabet to spin off core parts of Google’s advertising technology, pushing for the most sweeping breakup of a dominant tech platform since the government’s case against AT&T four decades ago. The remedies trial, overseen by U.S. District Judge Leonie Brinkema in the Eastern District of Virginia, opens a fresh phase in a legal saga that could reorder the business of buying and selling ads across the open web.

Prosecutors want Google to divest its AdX exchange and related tools that sit between publishers and advertisers, arguing that the company’s control across the ad tech stack has created an illegal conflict of interest: Google runs the market while also trading in it. The government says structural relief—a clean separation of businesses—is the only remedy capable of restoring competition to a market they say has been tilted for years by self‑preferencing and exclusionary contracts.

Google counters that a forced breakup would inject costly disruption into an ecosystem that supports millions of small businesses and publishers. The company proposes a package of behavioral and interoperability measures instead—opening up APIs, making auction code more transparent, and allowing broader use of rival tools—changes that, it argues, would address the court’s concerns without dismantling products that power the bulk of its revenue. Any divestiture, Google says, would create technical fragmentation, higher transaction costs, and fewer innovations at a moment when the industry is already in flux.

At stake is a machinery few consumers see but that quietly prices and delivers the ads that fund news sites, apps, and countless niche web services. Over the past decade, Google assembled a vertically integrated operation—ad server for publishers, exchange to run auctions, and tools for advertisers—that critics say allows it to steer trades toward its own venues and to glean data that competitors cannot match. Publishers contend that these dynamics depress the prices they receive for their inventory; advertisers say they pay more than they would in a genuinely neutral marketplace.

Judge Brinkema has already found that Google unlawfully maintained monopoly power in parts of the ad tech market. The question now is the cure. Remedies proceedings are typically narrow, but this one is unusually consequential because it arrives on the heels of a separate search antitrust case in which another court rejected structural relief and opted for behavioral constraints. Prosecutors argue that display advertising is different: the conflicts are hard‑wired into the architecture of real‑time bidding, and so only a structural fix will do.

For publishers, the trial is a referendum on the economics of the open web. Witnesses from local‑news groups and digital media firms are expected to testify that Google’s dominance leaves them little choice but to adopt its stack, surrendering data and bargaining leverage in the process. Some independent ad tech providers have lined up behind the government, saying a spin‑off would create space for competing exchanges and tools to thrive. Others warn that breaking the stack could slow ad delivery, complicate measurement, and bury smaller players in integration work.

Google’s defense leans heavily on the argument that competition is flourishing: Amazon and The Trade Desk are formidable in ad buying; Meta and TikTok pull budgets into walled gardens; and retail media networks have exploded into a third force competing for digital ad dollars. In this telling, Google’s share of open‑web display and video has been eroded by alternatives, and the government’s market definition ignores how rapidly advertisers move money toward performance channels when they see better returns.

Remedies proposals outline concrete engineering changes. The Justice Department wants Google’s ad auction mechanisms opened to outside scrutiny and proposes divestitures phased over time, starting with AdX and potentially including the DoubleClick for Publishers (DFP) ad server if competition does not materially improve within a set period. Google, by contrast, offers to publish interfaces, bolster data portability, and commit to non‑discrimination across its tools—enforceable, it says, through compliance reporting and independent monitoring. The gulf between those blueprints is exactly what the court must bridge.

Investors and the industry are gaming out multiple scenarios. A clean spin‑off of exchange operations could become a new, publicly traded entity—call it “AdXCo”—that runs auctions independent of Google’s media buying and publisher tools. That might boost rival exchanges and dampen accusations that the house always wins. But carving out interdependent systems is hard: identity frameworks, latency‑sensitive code paths, and massive data pipelines would need to be duplicated or renegotiated across company boundaries. A partial divestiture, or a behavioral consent decree with tough audits and API guarantees, would be simpler to execute but risks leaving core incentives intact.

The timing and the forum matter. The case is proceeding in the Eastern District of Virginia, known for its rocket docket, which could accelerate a final order even as appeals loom. Any structural relief would almost certainly be stayed pending appellate review, prolonging uncertainty for buyers and sellers. Meanwhile, regulators in Europe are pressing their own remedies on conflicts in Google’s ad tech stack, raising the possibility of a patchwork of rules that multinational publishers and advertisers must navigate.

Beyond courtroom choreography, the outcome will influence the next wave of ad technology, including the role of artificial intelligence in targeting and measurement as third‑party cookies fade. If the court forces separation, we could see a renaissance of neutral intermediaries and more experimentation with clean‑room data uses that reduce dependence on any single platform. If the remedy is behavioral, the burden will shift to detailed governance—audits, APIs, reporting—that tries to keep a sprawling system fair without tearing it apart.

For Washington, the case is a test of whether antitrust can grapple with software‑defined markets in which conflicts live in code and control over data can be as decisive as control over physical infrastructure. For Silicon Valley, it is a signal that enforcement pressure remains high even after mixed outcomes in other Big Tech cases. And for the open internet—still largely financed by ads—it is a crossroads moment that will shape who gets paid, who pays, and on what terms.

Whatever Judge Brinkema decides, the arguments in Alexandria underscore a broader reality: digital advertising has become critical infrastructure for the modern web. Whether it is run by one giant with guardrails or by a looser federation of competing services will determine not only where the money flows but also which kinds of media can survive. The government’s push for a spin‑off is an attempt to reset those rules. Google’s plea to avoid divestiture is an attempt to prove the rules can be fixed without breaking the machine.