Every time Apple gets comfortable charging for something built into the iPhone, someone eventually asks whether it really had to work that way.

This time, the group asking the question is particularly large: U.S. banks, credit unions, and other payment-card issuers that have paid Apple fees when customers use their cards through Apple Pay. A federal judge has now certified a class in an antitrust lawsuit against Apple, allowing qualifying financial institutions to pursue their claims together.

And yes, the dispute is about Apple Pay fees.

The lawsuit, originally filed in 2022, accuses Apple of using its control over the iPhone’s NFC hardware to keep competing mobile wallets from offering tap-to-pay functionality on equal terms. According to the plaintiffs, that left Apple Pay as the primary—and for the period at issue, effectively the only—way to make contactless payments with a card on an iPhone, giving Apple the ability to charge card issuers fees for transactions.

U.S. District Judge Jeffrey White certified the class on September 23. The class covers U.S. entities that issued payment cards enabled for Apple Pay and paid Apple a fee for transactions made using those cards. The judge also rejected Apple’s attempt to exclude expert testimony that the plaintiffs say supports their claims about Apple’s alleged monopoly power in the mobile-wallet market.

To be clear, class certification is not a finding that Apple violated antitrust law. It simply means the qualifying financial institutions can pursue the case collectively rather than having to bring essentially the same dispute against Apple one institution at a time.

That distinction matters because the potential class is enormous.

The fees at the center of the lawsuit are relatively small on an individual transaction but can add up across millions of payments. According to the complaint, Apple charges card issuers 0.15% on credit-card transactions made through Apple Pay and half a cent on debit-card transactions. On a $1,000 credit-card purchase, that 0.15% works out to $1.50.

The plaintiffs allege that Apple collects as much as $1 billion a year from these fees.

That figure is an allegation made in the lawsuit, not a finding by the court. But it explains why the case is getting considerably more interesting now that thousands of potentially affected financial institutions can pursue the claims as a group.

And this is where Apple’s old NFC strategy comes back into the conversation.

The plaintiffs argue that Apple was able to impose the fees because competing wallets couldn’t access the iPhone’s NFC functionality to provide their own tap-to-pay services. They point to Android as a contrast, where multiple mobile wallets can support contactless payments and card issuers aren’t charged an equivalent transaction fee by Google.

The basic argument is pretty straightforward: if banks had meaningful alternatives to Apple Pay on the iPhone, Apple would have had to compete for their business instead of being the unavoidable middleman for contactless payments.

Apple’s policies have changed since the lawsuit began, which adds another wrinkle.

Starting with iOS 18.1, Apple opened up access to the iPhone’s NFC and related payment technologies so eligible third-party developers could offer contactless payment functionality. Apple has expanded that availability across the U.S., Canada, Australia, Brazil, Japan, New Zealand, the U.K., the European Economic Area and other markets.

So the argument isn’t simply about what Apple allows today. The lawsuit also concerns Apple’s earlier restrictions and the fees that card issuers say they paid while those restrictions were in place.

The plaintiffs are seeking repayment of the fees they allege Apple improperly collected, along with an injunction that would address the practices challenged in the lawsuit.

Apple, meanwhile, has disputed the allegations and has continued to challenge parts of the plaintiffs’ case. The latest ruling doesn’t determine whether Apple actually violated antitrust law, whether the fees were unlawful, or whether the financial institutions are entitled to damages.

It does, however, make the fight substantially bigger.

Instead of a few credit unions knocking on Apple’s legal door, a much larger group of U.S. financial institutions can now participate in the same case. And considering how many people casually hold an iPhone up to a payment terminal every day without thinking about what happens behind that little animation, the economics of that tap suddenly look a lot more interesting.

Every time.

Apple Pay may feel like a tiny feature on the iPhone. In the courtroom, apparently, it’s a billion-dollar question.