In a new antitrust lawsuit against Google, the Justice Department accuses the tech company of sustaining an illegal monopoly over search and search advertising.

The New York Times reports that the suit will allege how Google used its power in search to harm customers—and that the company’s practice of guaranteeing it is the default browser on smartphones is anticompetitive.

Filed in a federal court in Washington D.C., the DOJ accused Google of illegally cultivating its dominance over search through a number of business contracts and agreements that shut out competition. These contracts include Google paying billions to Apple to ensure that the Google search engine is the default for iPhones. The suit claims that competition and innovation has suffered due to these contracts.

Jeffrey Rosen, the deputy attorney general who was in charge of the investigation, said Google “has maintained its monopoly power through exclusionary practices that are harmful to competition.”

“Google is the gateway to the internet and a search advertising behemoth,” he added.

The lawsuit isn’t a shock. Last year, the DOJ said it was looking into the competitive behavior of big tech platforms. Congress has also been examining large internet companies, with the House Judiciary Committee sharing its conclusions in early October. It found that Google, Amazon, Apple, and Facebook were exhibiting favorable treatment for their own services, and causing harm to competitors and small businesses. The committee also demanded new antitrust procedures to mirror the changes to the online economy. Google has consistently denied accusations of antitrust abuses.

This will be the government’s most significant challenge to tech industry dominance in a generation, since the Clinton-era DOJ confronted Microsoft’s market control in the late 1990s.

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