The Department of Justice (DOJ) and Google wrapped up the tech giant’s second antitrust trial in two years Monday, as the company seeks to fend off monopoly allegations in the advertising technology space.  After a relatively brief two-week trial in September, the two sides reconvened in U.S. District Judge Leonie Brinkema’s Alexandria, Va., courtroom for closing arguments, offering competing visions of how ad tech functions and Google’s role.  "This case is about two different versions of reality,” DOJ lawyer Julia Tarver Wood said.  The lawsuit, which was originally filed in 2023, centers on the tools used by website publishers and advertisers to sell and buy ad space online.  The DOJ identified three different markets — one for publishers to sell their ad space, one for advertisers to buy and place ads and one connecting publishers and advertisers. The agency argues that Google has a monopoly over all three markets.  “Google is once, twice, three times a monopolist,” DOJ lawyer Aaron Teitelbaum said Monday.  The government alleges that the tech giant achieved its dominant position by eliminating competitors through acquisitions, and then using this dominance to force more publishers and advertisers to use its services.    Google, on the other hand, argues that there is one, two-sided market between publishers and advertisers that extends well beyond online ads to include ads on apps, social media and connected television.  Within this market, the tech giant says it faces stiff competition from the likes of Microsoft, Meta, Amazon and TikTok.  To side against Google would mean overturning Supreme Court precedent, Google lawyer Karen Dunn said. She argued that the DOJ is attempting to make Google deal with its rivals, which would be at odds with the 2004 Supreme Court decision in Verizon v. Trinko.  She also pointed to the 2018 decision in Ohio v. American Express, in which the court ruled that the credit card industry consisted of a single, two-sided market. Brinkema appeared skeptical of that argument, suggesting that the Google case appears to be a “completely different setup.” However, she also pushed back against the DOJ’s assertion of three distinct markets in the ad tech space.  The judge will ultimately decide the case, which received a bench trial after Google submitted a $2.3 million check in June to cover potential damages.  The decision in the ad tech case could be crucial for Google, which suffered a major loss in August when a federal judge found that it maintained an illegal monopoly over online search.  The DOJ has asked the judge in the search case to order Google to sell off its Chrome business, arguing that the tech giant’s ownership and control of the browser stands in the way of its efforts to open up the market.  Kent Walker, Google’s chief legal officer and president of global affairs, called the potential breakup a “staggering proposal,” contending that it goes well beyond the decision in the case and would break Google’s products.  In both cases, the tech giant has come under scrutiny over its handling of internal communications.   Google has faced accusations that it destroyed relevant evidence due to its practices of automatically deleting instant messages and relying on employees to turn off this feature when facing litigation. Some have also suggested the tech giant overused legal privilege to shield documents.  At the ad tech trial, Brinkema lamented that “an awful lot of evidence has likely been destroyed,” according to The New York Times.  However, Google argued in a statement to the Times that it has responded comprehensively to inquiries and litigation over the years, producing millions of documents in the DOJ’s two antitrust cases.