The US Justice Department on Tuesday filed an antitrust lawsuit against Alphabet's Google alleging that the Big Tech company has sought to defeat its rivals in the online advertising business using anti-competitive tactics for 15 years.

The Justice Department and a group of eight states including Virginia, California, Colorado, Connecticut, New Jersey, New York, Tennessee and Rhode Island have filed a lawsuit accusing it of illegally abusing a monopoly over the technology that powers online advertising.

The lawsuit filed by the US government claims Google “corrupted legitimate competition in the ad tech industry by engaging in a systematic campaign to seize control of the wide swath of high-tech tools used by publishers, advertisers and brokers, to facilitate digital advertising.”

The government alleges that Google's plan to assert dominance has been to “neutralise or eliminate” rivals through acquisitions and to force advertisers to use its products by making it difficult to use competitors' products.

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This includes its 2007 acquisition of DoubleClick, a dominant ad server, and subsequent rollout of technology that locks in the split-second bidding process for ads that get served on Web pages.

“Monopolies threaten the free and fair markets upon which our economy is based. They stifle innovation, they hurt producers and workers, and they increase costs for consumers,” Attorney General Merrick Garland said at a news conference Tuesday.

Garland added that for 15 years Google has “pursued a course of anti-competitive conduct” that has stalled the rise of rival technologies and manipulated the mechanics of online ad auctions to force advertisers and publishers to use its tools.

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In so doing, he added, Google ”engaged in exclusionary conduct” that has “severely weakened,” if not destroyed, competition in the ad tech industry.

This is the second antitrust lawsuit filed by US officials against Google and the fifth major case in the US challenging the company’s business practices.

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