A narrowly divided Supreme Court is allowing a group of consumers to move forward with a lawsuit charging that Apple overcharges customers for app store purchases. Apple had asked courts to throw out the lawsuit, arguing that the law only allowed app developers, not customers, to bring such a case.

The lawsuit has been underway since 2011 and is nowhere close to resolution. The stakes are high. Apple iOS platform is notable for completely shutting out alternative means of app distribution. Other major software platforms—including Android, Mac OS, and Windows—offer customers the option to download and install software they acquire from third parties without paying a commission to the platform owner. But jailbreaking aside, iPhone users have no way to install apps other than through the official App Store.

Plaintiffs in this case argue that Apple’s 30 percent commission on app sales wouldn’t be viable in a competitive app distribution market. The class-action lawsuit seeks refunds on behalf of millions of users who have paid inflated prices for apps as a result of Apple’s exclusionary practices.