A group of US consumers has been given the go-ahead by the Supreme Court to sue Apple over app prices.
The iPhone users argued that there is no alternative place to buy an iPhone app, but that Apple takes a 30% commission on every sale, so therefore they are being overcharged.
They claim that this puts Apple in breach of anti-trust laws.
Apple said that it was an agent for app developers and that it neither owned nor sold the apps itself.
However, while app developers set their own prices, Apple collects the payments.
One of the judges who ruled against Apple was President Donald Trump's controversial appointment, Brett Kavanaugh.
"Leaving consumers at the mercy of monopolistic retailers, simply because upstream suppliers could also sue the retailers, would directly contradict the long-standing goal of effective private enforcement in anti-trust cases," he said.
The suit, filed by leading plaintiff Robert Pepper, dates back to 2011.
According to statistics portal Statista, US customers spent $46.6bn (£36bn) on a combination of in-app purchases, subscription and premium apps in 2018.