(Bloomberg) -- The US government may never get a better chance to rein in Google. Its lawsuit to break the company’s chokehold on the digital advertising market was more than a decade in the making and will set the tone for antitrust enforcement for years to come.

It also represents the culmination of one man's life work. Justice Department antitrust chief Jonathan Kanter, 49, has spent the bulk of his career seeking to limit the economic harm caused by giant tech platforms that thwart competition. Now he’s in a position to make it happen.

Since his start as a young antitrust lawyer in Washington, Kanter has focused on the online world and Google in particular, becoming one of the most knowledgeable and respected legal experts on how the biggest companies exploit data from users and business partners to churn out rich profits.

The roots of the case brought by Kanter go back more than a decade, and the dispute is likely to last well beyond his time at the agency and perhaps the Biden administration itself. The lawsuit filed last week in Virginia federal court seeks to end Google’s dominance of the ecosystem that underpins much of online advertising by forcing parent company Alphabet Inc. to sell off parts of its ad business and unwind three key acquisitions, including the pivotal 2007 purchase of online advertising giant DoubleClick for $3.1 billion.

Proponents of the crackdown see it as a prime opportunity for antitrust officials to reassert their authority over technology companies like Google, Meta Platforms Inc. and Amazon.com Inc. that have grown at warp speed and reach into so many aspects of daily life that they often seem more powerful than the governments charged with overseeing them. Tech critics view federal prosecutors as the best hope for bringing the industry to heel after US lawmakers failed to pass meaningful competition laws last year, and are counting on the Justice Department to protect advertisers, publishers and ultimately consumers themselves from monopolistic practices that cost them money.

The feds have been outgunned, outmaneuvered and outspent by the tech industry and its army of high-end lawyers for years now, and reversing that trend to win a lawsuit will be no easy feat. The advertising business that Kanter wants Google to sell is a growing division and accounted for more than 23% of the company's total revenue in 2021. Google denies the allegations, arguing that the agency will undermine “the highly competitive advertising technology sector.”But Kanter entered the Justice Department in 2021 determined to return enforcement to the trust busting tenor of the early 20th century, while carrying out President Joe Biden’s mission to increase competition after decades of consolidation. He is counting on an unusual tactic to overcome the disadvantages — demanding  a jury trial with the idea that ordinary citizens fed-up with tech’s power can easily understand the concept of fairness and will be eager to crack down on anti-competitive practices.

“We are witnessing the most aggressive enforcement of antitrust laws that we’ve seen in decades thanks to champions like Jonathan Kanter,” said Democratic Senator Elizabeth Warren of Massachusetts. “Kanter is not afraid to hold giant corporations accountable for illegal behavior, and he’s doing what it takes to spur competition.”

Still, the stepped-up enforcement push faces an uphill climb in the courts, as evidenced by a judge’s ruling Wednesday against the US Federal Trade Commission’s effort to block Meta from buying virtual reality startup Within Unlimited.

The new Google lawsuit follows a similar case against its search business brought under former President Donald Trump. That complaint, filed by the Justice Department and several state attorneys general in October 2020, alleges the company has illegally monopolized the online search market by paying browser makers and smartphone manufactures like Apple Inc. to ensure its search engine is set as the default. That case is set for trial in September.

While Google’s roots are in search and the business continues to be a major profit center, analysts see the advertising case as potentially more worrisome for the company. Search ads, which appear on the top and side of a results page, account for a larger share of Google's revenue today, but their growth is expected to slow in the coming years, while display ads will provide a greater share of ad revenue in 2023 and beyond. The remedy being sought by prosecutors in this case — forcing Google to sell off large parts of the advertising platform entirely — is more extreme.

The Justice Department says its demands are justified because of Google's dominant position in the $278.6 billion US digital-ad market. It says that control allows Google to keep at least $0.30 of every dollar advertisers spend through its online advertising tools.Kanter was a “pioneer” in understanding how Google’s control over the technology contributes to its power, said Cristina Caffarra, an economist who advised the Texas attorney general on its antitrust case against Google. “He understands deeply the plumbing, what’s actually at play,” said Caffarra, European managing partner of advisory firm Keystone Consulting.

The case has its origins in Google’s purchase 15 years ago of DoubleClick, whose software served as the middleman between publishers and advertisers. Instead of a content producer — like a blog or newspaper’s website — having to hire a sales staff, set rates and persuade businesses to advertise, Google would take care of all that.

The US Federal Trade Commission looked into the purchase, but ultimately waved it through. In the years that followed, Kanter was working as a lawyer with Cadwalader, Wickersham & Taft LLP, and was pressed into service by Microsoft Corp., which perceived Google as an existential threat. Kanter was called on to explain Microsoft’s concerns to policy makers, meet with officials and draft testimony. A raft of other firms including Yelp Inc., Tripadvisor Inc. and Facebook -- since renamed Meta Platforms — also voiced their objections to Google’s dominance. 

A broader FTC investigation into Google’s practices was closed without action in 2013 and Microsoft CEO Satya Nadella decided to make peace with Google in 2016 after a decade of fighting. Kanter jumped to Paul Weiss Rifkind Wharton & Garrison LLP to continue work on antitrust issues and picked up other clients searching for someone to articulate their concerns about Google. Over time the roster grew to include News Corp., Mapbox Inc. and the digital publisher IAC Inc., among other companies.

While Trump was a frequent critic of the largest tech platforms during his campaign and after he was elected, it wasn’t until his second attorney general, Bill Barr, took over at the Justice Department in February 2019 that Google came under serious scrutiny. Barr eventually decided to prioritize the search case, in a move to accelerate an enforcement action.The fate of the Justice Department advertising probe remained in limbo for months after Biden took office as the administration debated who should head the antitrust division. In July 2021, the president nominated Kanter for the post, but the Senate took another four months to confirm him, which it ultimately did, 68-29.

Within hours of Kanter’s confirmation, Google asked the Justice Department to ascertain whether he should be barred from their cases because of his prior work for Google antagonists. The agency isolated him from the Google search lawsuit and the ad tech probe for more than a year as officials mulled how to handle the potential ethics issue. Kanter’s top deputy, Doha Mekki, was put in charge of the probe. The Justice Department ultimately cleared Kanter to work on the cases late last year, allowing him to help shape and sign the complaint filed last week.

Google isn’t likely to be the only major company challenged by the Justice Department’s antitrust team. The agency began probing Apple during the Trump administration over concerns about its app store, and under Kanter has opened or expanded probes into Live Nation Entertainment Inc.’s Ticketmaster and Visa Inc.The Justice Department’s new complaint is the strongest one yet, telling a “elaborate and nuanced story about” how Google built up its control over the world of advertising technology, said Bill Kovacic, a former FTC Republican commissioner who regrets voting to allow Google’s DoubleClick deal. But it will still be challenging for the government to prevail, he said.“Undoing the harm will be very difficult,” Kovacic said. “Not impossible but very difficult.”

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