A group of 35 states, along with Microsoft, the Electronic Frontier Foundation and other organizations, have thrown their support behind Epic Games in the Fortnite maker’s legal battle with Apple. In a brief filed Thursday with the US Court of Appeals for the Ninth Circuit, attorneys general for the states argued that the court should overturn the earlier ruling that Apple’s control over its App Store doesn’t violate antitrust laws.

«Apple’s conduct has harmed and is harming mobile app developers and millions of citizens,» they wrote in the brief.

Apple and Epic have been locked in a court fight over how much control the iPhone maker should have over its App Store. Last year, Epic unsuccessfully argued to a US District Judge in California that Apple should be forced to allow app developers more freedom in how they offer apps to iPhone and iPad owners. However, the judge said Apple’s rules against allowing developers to direct users to other payment systems was anti-competitive, and issued an injunction to allow developers to do so in their apps.

In December, Apple scored another win when the Court of Appeals for the Ninth Circuit agreed to delay that injunction. Apple now has until its appeals process with Epic concludes, which could take years.

Critics of Apple, meanwhile, continue to make their case.

«Apple continues to monopolize app-distribution and in-app payment solutions for iPhones, stifle competition, and amass supracompetitive profits within the almost trillion-dollar-a-year smartphone industry,» the attorneys general wrote in the brief.

Apple said it expects Epic’s challenge will fail.

«We’re optimistic that the ruling will be affirmed on appeal,» said an Apple spokesperson in an emailed statement on Friday. «We remain committed to ensuring the App Store is a safe and trusted marketplace for consumers and a great opportunity for developers.»

In total, 10 briefs were filed in the case on Thursday. Microsoft argued that ruling in favor of the iPhone maker could let the company leverage its «control of iOS to foreclose competition» in adjacent markets.

«If Apple is allowed to step between any company with online services and users of iPhones, few areas of the vast mobile economy will be safe from Apple’s interference and eventual dominance,» wrote Microsoft.

The US Department of Justice, which also filed a brief, declined to take a position on the merits of Epic’s and Apple’s arguments, but said the district court «committed several legal errors that could imperil effective antitrust enforcement, especially in the digital economy.» The DOJ specifically called out the court’s interpretation of the Sherman Act, a key US antitrust law passed in 1890, saying it was read «narrowly and wrongly.»

Epic Games declined to comment on the briefs.