The United States government is taking on one of the world's most powerful companies: Google.

A court battle kicks off on Tuesday in which the U.S. Justice Department will argue that Google abused its power as a monopoly to dominate the search engine business. It's the government's first major monopoly case to make it to trial in decades and the first in the age of the modern internet.

The Justice Department's case hinges on claims that Google illegally orchestrated its business dealings, so that it's the first search engine people see when they turn on their phones and web browsers. The government says Google's goal was to stomp out competition.

"This lawsuit strikes at the heart of Google's grip over the internet for millions of American consumers, advertisers, small businesses and entrepreneurs beholden to an unlawful monopolist," said former Attorney General William Barr when the case was first filed in October 2020.

Now nearly three years later, with millions of pages of documents produced and depositions from more than 150 people, the case is going to trial.

How the internet is run is at stake

The government's case challenges how tech companies are able to amass power and control the products people now use daily in their lives. The outcome of the case could change how tech giants are able to do business and, in effect, how the internet is run.

Google, which is worth $1.7 trillion, controls around 90% of the U.S. search engine market. It's put together a massive legal team and brought on outside law firms to help fight its case.

The company says its search product is superior to competitors and that is why it dominates the industry. Google says if people don't want to use its search engine, they can just switch to another.

"People don't use Google because they have to — they use it because they want to," Kent Walker, one of Google's top lawyers and its president of global affairs, wrote in an emailed statement. "It's easy to switch your default search engine — we're long past the era of dial-up internet and CD-ROMs."

Echoes of the Microsoft case, which the government won

The last antitrust case of this magnitude took place in 1998, when the Justice Department sued Microsoft. That trial centered around claims that Microsoft illegally grouped its various products together in a way that both stifled competition and compelled people to use its products.

The judge ruled in favor of the Justice Department in that case, saying Microsoft violated antitrust laws and held "an oppressive thumb on the scale of competitive fortune."

The Justice Department's case against Google is strikingly similar and its lawyers are angling for the same outcome.

"That case was about a monopolist tech platform and the government won," says Rebecca Haw Allensworth, a professor at Vanderbilt Law School who specializes in antitrust law. "And so, everybody has viewed that as a kind of blueprint for how we might enforce the laws against the current tech giants."

"This is a real test of whether or not that theory works," Allensworth added.

Google's exclusive deals with Apple & Samsung

The case against Google focuses on the company paying billions of dollars each year for exclusive agreements with phone makers, like Apple and Samsung, and web browsers, like Mozilla, which runs Firefox.

Those agreements let Google be the default search engine on most devices. The Justice Department say that by securing this position, Google has been able to box out smaller rivals.

DuckDuckGo is one of those smaller rivals. It has centered its search business around privacy and ensuring users aren't tracked — unlike Google, which has long tracked users for targeted advertising. Kamyl Bazbaz, DuckDuckGo's vice president of public affairs, says she's glad this case is headed to trial.

"Google has used its monopoly power to block meaningful competition in the search market by putting a stranglehold on major distribution points for more than a decade," Bazbaz wrote in an email. "So even though DuckDuckGo provides something extremely valuable that people want and Google won't provide — real privacy — Google makes it unduly difficult to use DuckDuckGo by default."

A 3-month trial without a jury and the judge will rule

After the Justice Department filed its case against Google in 2020, a group of 35 states, along with Guam, Puerto Rico and the District of Columbia, filed a near identical suit against Google. That suit will be tried with the Justice Department's claims and also be heard at the trial kicking off on Tuesday.

Lawyers for the Justice Department are expected to cover the history of Google and how it became one of the most powerful companies on earth.

"Two decades ago, Google became the darling of Silicon Valley as a scrappy start-up with an innovative way to search the emerging internet," the Justice Department wrote in its initial complaint. "That Google is long gone."

Witness lists haven't yet been released but it's expected that Google CEO Sundar Pichai will testify. Top executives from other tech companies are also expected, including Apple's Eddie Cue.

Judge Amit Mehta will preside over the trial; he was appointed by President Barack Obama in 2014. It's a bench trial, so there's no jury and Mehta will give the final ruling. The trial is slated to last about three months.

If Judge Mehta rules in favor of the Justice Department, it's still unclear how he'd sanction Google. It could be anything from fines to a restructuring of the company, which could ultimately affect how people experience the internet.

Editor's note: Apple and DuckDuckGo are among NPR's financial supporters.