Will advertising, Google's cash cow, also be its main problem? This Thursday, the US justice system ruled in a 115-page decision that Google knowingly implemented a series of anti-competitive actions to establish and maintain its monopoly power in the markets for ad servers for publishers (DoubleClick for Publishers or DFP) and ad exchange platforms (AdX), by tying them together, making it difficult, if not impossible, for competing alternatives to prosper.

Practices such as "First Look", which gave AdX priority access to the most profitable ad impressions, and "Last Look", which allowed Google to bid last after seeing competitors' bids, were singled out as mechanisms that gave Google an unfair advantage. Judge Brinkema stressed that these actions prevented competition from developing, deprived publishers of potential revenue and artificially strengthened Google's market position.

For those who missed the beginning of the story: in 2008, Google bought DoubleClick for $3.1bn. The aim was to strengthen its advertising delivery capabilities and speed up the marketing of its products for advertisers and publishers. The deal also prevents Microsoft from getting its hands on a strategic player, perceived as a serious threat to Google's advertising business. DoubleClick brought with it its flagship product, DoubleClick for Publishers (DFP), which at the time equipped nine of the ten largest American websites and held a 60% market share. The acquisition enabled Google to massively expand its base of third-party publishers and consolidate its control of the sales side of the market. It also gives Google access to AdX, a nascent advertising exchange connecting advertisers and publishers. By linking DFP to AdX and integrating it with AdWords, Google gains scale, network effects and influence.

This conviction in the digital advertising sector comes on the back of another legal setback for Google, which was already found guilty of anti-competitive practices in online search by a federal court in Washington last August.

Google intends to appeal

Google quickly indicated its intention to appeal the decision. Google vice president Lee-Anne Mulholland said the company disagreed with the court's decision regarding its publisher tools, but claimed it had won half the case. Although the original complaint also alleged monopolisation or attempted monopolisation of the advertiser ad network market, the decision indicates that the court did not find Google liable on this count

This decision paves the way for important discussions regarding sanctions to be imposed on Google to remedy this monopoly situation. The US Department of Justice (DOJ) is expected to present a remedy plan, and hearings are scheduled to determine the penalty.

Among the remedies being considered, the demerger of Google's advertising business, including the sale of DoubleClick and AdX, is an option being seriously considered by the DOJ. Before the trial, Google reportedly even proposed to the European Commission that it sell its AdX ad exchange system. Such a dismantling of Google's "powerful advertising machine" would profoundly disrupt the online advertising market.

Other potential measures include limiting or banning commercial agreements signed with giants such as Apple and Samsung, which make Google the default search engine on their devices. The obligation to share certain data with its competitors, such as its search index, is also on the table.

If Google loses on appeal, the consequences could be considerable:

- structural dismantling: Google could be forced to divest key assets in its advertising business, reducing its control over the entire value chain.

- major organisational changes: the company may have to make significant changes to its organisation and business practices.

- increased openness to competition: the end of the forced integration between DFP and AdX could allow third-party players to compete more fairly.

- greater transparency: Google could be subject to increased transparency and openness obligations in the advertising market.

This US condemnation resonates with similar concerns expressed by competition authorities in Europe and the UK. In the UK, Google is the target of a large-scale class action for abuse of a dominant position in the online search sector. Filed with the Competition Appeal Tribunal in April 2025, the claim seeks up to £5bn (around $6.6bn) in damages. It accuses the US giant of foreclosing the market by striking deals with manufacturers to pre-install Google Search and the Chrome browser on Android devices, and paying large sums to Apple to remain the default search engine on iPhones. The suit also alleges that Google gave its own advertising service a technical advantage over those of its competitors.

For its part, Google rejects the accusations as "speculative and opportunistic" and intends to defend itself vigorously. The proceedings come after the Competition and Markets Authority had already launched an investigation in January into the group's practices in search services and their impact on advertising markets.

In March 2025, the European Commission published a preliminary study according to which Google's search engine systematically favoured its own services, to the detriment of those of its competitors, in breach of the Digital Markets Act (DMA). Brussels also criticised Google Play for limiting the ability of application developers to direct consumers to other channels, where more advantageous offers could be made. Alphabet, Google's parent company, faces penalties of up to 10% of its worldwide turnover, or 20% in the event of a repeat offence. Google has disputed the charges, arguing that the requested changes would harm both the user experience and the traffic generated for European businesses.

This article was originally published in .