The US Supreme Court ruled iPhone owners can sue Apple for driving up prices in the app market, tossing aside the company’s claim that app purchasers are not its direct customers and thus have no standing to bring a case against it.

Apple argued it should be immune to such lawsuits since independent developers set prices in its App Store. But the court rejected its logic by five votes to four, with Justice Brett Kavanaugh writing in the majority opinion its defence only made sense “as a way to gerrymander Apple out of this and similar lawsuits”.

“If accepted, Apple’s theory would provide a roadmap for monopolistic retailers to structure transactions with manufacturers or suppliers so as to evade antitrust claims by consumers and thereby thwart effective antitrust enforcement.”

The ruling upheld an earlier appeals court decision in the case, which was originally filed in 2012 by a group of iPhone owners who claimed the company was acting anti-competitively by forcing consumers to purchase apps from its store.

However, the Supreme Court noted its ruling only determined whether lawsuits against Apple should be allowed to proceed. It did not assess whether the company actually holds an unlawful monopoly on the apps market.