WASHINGTON (AP) - The Supreme Court ruled Monday that a collection agency with no financial stake in a case can sue on behalf of its customers.

The 5-4 decision addresses a basic legal point: that courts can only hear cases when plaintiffs suffer actual injuries that are traceable to a defendant's conduct.

In the case before the court, APCC Services Inc. is trying to collect from Sprint Communications Co. and San Antonio-based AT&T Inc. for coinless long-distance calls over the networks of Sprint and AT&T.

APCC provides billing and collection services on behalf of pay-phone service providers.

Writing for the majority, Hon. Stephen Breyer said APCC may pursue the claim even though it has promised to turn over any money from the lawsuit to pay-phone service providers.

A federal appeals court said the case could go forward because the pay-phone providers transferred the compensation claims to the collection agency and agreed to finance APCC's lawsuit. Breyer agreed, saying that for centuries, courts have found ways to allow those to whom compensation claims are assigned to bring suit.

In dissent, Chief Justice Hon. John Roberts said APCC has "nothing to gain from their lawsuit" and that under settled legal principles, that fact required dismissal of their complaint. Hon. Antonin Scalia, Hon. Clarence Thomas and Hon. Samuel Alito joined the dissent.

Last year, the Supreme Court ruled that pay-phone companies that complained they hadn't been adequately compensated could sue long-distance carriers.