An Apple spokesperson said in a statement to Fortune that the App Store "has fueled competition and growth in app development", which created millions of jobs and resulted in over $100 billion in payments to developments worldwide.
The plaintiffs argue that Apple's developers would be unable to sue Apple due to the firm controlling their means of revenue, which leaves the consumers as the only one who can challenge the firm in court.
But it didn't seem to satisfy liberal members of the court.
But Associate Justice Sonia Sotomayor said the customer pays the commission, adding, "This is a closed loop with Apple as its spoke".
Wall countered that the first sale was between the app creator and Apple, when making pricing decisions.
Justice Elena Kagan made similar comments.
That relationship makes Apple the proper target of an antitrust lawsuit, they said.
Anyone who wants to get an app for an iPhone has only one place to go - Apple's own App Store. I pay Apple directly with credit card information that I've supplied to Apple. Both said they were skeptical of the 1970s-era rule that bars antitrust suits against manufacturers if consumers bought their products through middlemen, not directly from the maker.
However, a few of the justices expressed some skepticism with Apple's arguments.
A trial court initially dismissed the suit.
However, the plaintiffs would still have to convince district judges that Apple is exploiting a monopoly, and attempt to prove that the company's 30pc commission has raised app prices. That group said the customer "is unequivocally buying from the app developer, not the platform the developer sold their app through".
"The plaintiffs, as well as antitrust watchdog groups, said closing courthouse doors to those who buy end products would undermine antitrust enforcement and allow monopolistic behavior to expand unchecked".
"They happen to be the largest company in the world, or at least they were some weeks ago, and they are able to extract monopoly pricing by virtue of a unique e-commerce monopoly on their App Store", said Frederick. A judge could triple the compensation to consumers under antitrust law if Apple ultimately loses the suit.
But Apple's critics say its control over the App Store makes it unlike other internet marketplaces.
Conservative Chief Justice John Roberts' questions suggested he agreed with Apple's position.
They say that by charging 30 per cent commission for apps sold through their store, Apple was effectively engaging in price gouging that was passed on to customers.