Google is facing even more legal trouble as it prepares for another trial, this time focused on its Play Store and potential antitrust issues.

On Monday, Google will attempt to safeguard a valuable aspect of its online domain while also navigating the ongoing legal proceedings of the largest antitrust case in the United States in 25 years.

A 10-person jury in a San Francisco federal court will determine if Google’s digital payment system in the Play Store, which distributes apps for Android phones, is breaking the law by causing increased costs for consumers and developers.

The hearing in front of U.S. District Judge James Donato is set to run until right before Christmas and feature statements from former Google executive Sundar Pichai, currently the CEO of Alphabet Inc, Google’s parent company.

Pichai recently took the witness stand in Washington D.C. during an antitrust trial pitting Google’s long-running dominance of internet search against the U.S. Justice Department’s attempt to undercut it on the grounds the the company has been abusing its power to stifle competition and innovation.

Epic Games, the creator of the widely known video game Fortnite, is pursuing a lawsuit against Google’s Play Store. This case is similar to a previous trial in 2021 that involved Apple’s iPhone app store and addressed many of the same concerns.

While a federal judge mainly ruled in favor of Apple during the trial, the result did reveal a potential weakness in the iPhone’s otherwise strong digital security.

Both the judge and an appeals court concluded that Apple must permit apps to include links to alternative payment methods, potentially jeopardizing the 15% to 30% fees that both Apple and Google currently collect on in-app digital purchases. Apple is appealing this decision to the U.S. Supreme Court, where Epic is also challenging the majority of the case that they initially lost.

Epic is currently targeting Google’s commission structure, despite the fact that Android software already allows for other stores, like Samsung’s pre-installed on its devices, to distribute apps compatible with the operating system. However, Epic claims that Google still holds a dominant position in the Android app market and its associated payment system, and has spent hundreds of millions of dollars to suppress competition.

Similarly to Apple’s actions during its trial, Google justifies its fees as a means of receiving compensation for the funds it puts into its Play Store. It also argues that the regulations in place are necessary to safeguard the security of the millions of individuals in the United States who use Android-powered phones to download apps.

Initially, Google was set to face multiple opponents in the trial. However, in September, it reached a settlement regarding allegations made against the Play Store by state attorneys general. Just last week, it also resolved a case brought against it by Match Group, the company behind Tinder and other online dating platforms.

Google changed their request for a jury trial to a decision made by the judge after the Match settlement, but Donato rejected the proposal.

Match will be given $40 million and implementing Google’s “user choice billing” system as part of their agreement. The details of the settlement with the state attorneys general will be announced during Google’s trial with Epic.

In a post on social media, Tim Sweeney, the CEO of Epic, criticized the “user choice billing” option as a deception and promised to take legal action against Google. It is anticipated that Sweeney will also give testimony in court during the trial.

In a blog post, Wilson White, the vice president of government affairs and public policy at Google, criticized Epic for attempting to gain without giving in return. White noted that Epic had already failed in their main argument against Apple and went on to condemn the game developer for taking a chance with Android with a case that is even weaker.