The trial in a landmark antitrust case against Google is scheduled to start on Tuesday in Washington district court over charges of monopolizing the online search space.

The suit, filed by the US justice department in 2020, represents the biggest legal challenge to the power and influence of big tech in decades, and could be a bellwether in the fight against the industry’s monopolies.

“The Google search trial will be hugely consequential for our digital world where the outcome will determine how millions of Americans access and use the internet,” said Katherine Van Dyck, senior counsel at the American Economic Liberties Project, a non-profit that filed a motion to make court proceedings public due to the importance of the case.

The justice department has accused Google of using its market power to unfairly lock out rivals and position itself as a gatekeeper of the web. The case marks the first brought by the government against Google to go to trial. The justice department has also joined a separate case against Google brought by the attorneys general of 38 states and territories over monopoly concerns in advertising.

Google has denied wrongdoing in both cases and did not immediately respond to a request for comment. The justice department did not immediately comment.

In filings unsealed last month, Judge Amit P Mehta tossed out a handful of charges brought against Google, narrowing the case in a slight victory for the company. He said Google was not required to defend itself against charges that the design of its search results page has harmed rivals such as Expedia or Yelp.

Still, Mehta allowed some of the more significant charges to proceed, including key arguments that Google’s exclusive contracts with phone manufacturers allegedly harmed competitors. The department alleges the company pays billions each year to “secure default status for its general search engine and, in many cases, to specifically prohibit Google’s counterparties from dealing with Google’s competitors”.

Mehta said in an opinion unsealed in August that Google’s “brand name has become so ubiquitous that dictionaries recognize it as a verb”. He said Google in 2020 had nearly 90% of market share and advertisers spend over $80bn annually alone to reach general search users.

“A company with monopoly power acts unlawfully only when its conduct stifles competition”, Mehta wrote.

The judge said the justice department is required to show that each particular action – for example, how Google handles search advertising – is a violation of antitrust law. This means that the government cannot show a string of actions and argue that these cumulatively break antitrust law.

“We look forward to showing at trial that promoting and distributing our services is both legal and pro-competitive,” said Kent Walker, Google’s chief legal officer, in response to Mehta’s decision.

While big tech has remained largely unscathed over the past few decades of unfettered success, lawsuits including these against Google could mark a changing of the tides. Attorneys general filed an antitrust suit against Meta that was thrown out earlier this year. The Federal Trade Commission, under new antitrust leader Lina Khan, also filed a suit against Amazon earlier this year.

The outcome of the Google case, the first major one of its kind to have its day in court, could be seen as a sign of to what extent those tides will turn.

Reuters contributed reporting