The conflict over the App Store is reaching a critical point.

Last year, Epic Games, creators of the critically successful multiplayer game Fortnite, launched a campaign against Apple for the way they manage their App Store. Specifically, they protested the fact that the App Store takes a 30% cut of all in-app purchases by offering their own workaround purchase system. Apple banned Epic from their store for this, but Epic, in turn, began gathering support from both other disgruntled app makers and US legislators to take Apple to court. That trial begins today.

Opening statements will be issued at 8:30 AM Pacific time, and the trial is projected to last approximately three weeks. U.S. District Judge Yvonne Gonzalez Rogers will be presiding over the case in Oakland, California.

Epic has obtained support from other companies that have made their grievances with the App Store’s financial structures public, such as Spotify, Tile, and Match. Both Epic and these companies have claimed that Apple’s policies are anti-competitive, and that if a company weren’t able to pay the App Store’s fees, they’d have no way to sell their product on it. Both Republican and Democratic senators have also chimed in, questioning Apple executives in a lengthy Senate hearing two weeks ago. Senator Amy Klobuchar went as far as to say that Apple’s App Store policies made the service a “literal monopoly”.

As far as who is more likely to win the case, experts believe Apple has the edge, but the losses could be substantial if they don’t win.

“I do think that on legal grounds, Apple is in a very good position,” says tech blogger John Grubber, “But the risk is very high because [if they lost] it would disrupt the whole business model of the app store”.

“Antitrust law, as it’s practiced in the US, is a complete mess,” says anti-monopoly activist Matt Stoller. “So we have no idea. The law basically depends on what the judge had for breakfast.”