Apple's store is far from the only one that takes a cut from developers. The group of plaintiffs argued that developers priced their apps higher than they otherwise would to account for Apple's commission.
With Monday's ruling, it will kick the case back to a lower court, where iPhone owners and Apple will continue what is likely to be a lengthy legal battle.
Apple´s online marketplace is the sole avenue for apps for its iPhone and other mobile devices, and the company has paid out more than $100 billion to developers since launching the store a decade ago. In an earlier hearing, Justices Stephen Breyer, Elena Kagan, and Sonia Sotomayor questioned Apple's reference to the Illinois Brick doctrine, relating to direct versus indirect purchasers.
"Apple's line-drawing does not make a lot of sense, other than as a way to gerrymander Apple out of this and similar lawsuits", Justice Brett Kavanaugh wrote.
This meant, for example, a consumer could sue a retailer, but not a wholesaler or a manufacturer of a product.
The court has not declared Apple monopolists yet, but this ruling does allow the case to proceed.More news: Tanker collision, gasoline spill closes portion of Houston Ship Channel
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Customers walk past an Apple logo inside of an Apple store at Grand Central Station in NY, U.S., August 1, 2018.
Dissenting from the decision, conservative Justice Neil Gorsuch, said the decision is "not how antitrust law is supposed to work" because it gives a green light to the exact type of case that the court had previously prohibited.
Tom's Hardware has reached out to Apple for comment, but did not receive an immediate response.
This story will be updated if or when Apple responds. If an app is overpriced, the fault lies with developers and not Apple, the iPhone maker claimed. A judge could triple the compensation to consumers under antitrust law if Apple ultimately loses the suit.
The Ninth Circuit, however, said that Apple is indeed the seller, through their App Store.
The case is Apple Inc. v Pepper, 17-204.