The Supreme Court on Monday ruled 5-4 against Apple in a case involving its signature electronic marketplace, the App Store, allowing iPhone users to move forward with their suit against the company.

The iPhone users argued that Apple’s 30% commission on sales through the App Store is passed along to consumers, an unfair use of monopoly power that ultimately results in inflated prices.

Apple argued that only app developers, and not users, should be able to bring such a lawsuit. But the Supreme Court, in an opinion authored by Justice Brett Kavanaugh, rejected that claim.

“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,” Kavanaugh wrote.

Shares of Apple, already battered by trade concerns, were down more than 5%, lagging the broader market.