WASHINGTON, Jan 9 (Reuters) - The U.S. Supreme Court agreed on Friday to hear a dispute involving fines imposed by the Federal Communications Commission on major U.S. wireless carriers for sharing customer location data without consent in the latest case to reach the justices challenging the powers of a U.S. regulatory agency.

The legal fight concerns whether the FCC's ‌pursuit of tens of millions of dollars in penalties against carriers such as Verizon Communications ( VZ ) and AT&T ( T ) - before the accused companies had their ​day in court - exceeded the federal agency's authority under the U.S. Constitution.

The justices are expected to hear ‍arguments and rule by the end of June.

The dispute marked the latest ⁠case to test whether a ⁠federal agency's in-house enforcement scheme violates provisions of the Constitution ensuring a defendant's right to a jury trial.

The case stems from nearly $200 ‌million in fines that the FCC imposed in 2024 ​against major U.S. wireless carriers after the agency found they had sold access to customer location data to third parties without securing users' consent.

The penalties included an $80 million fine ⁠to T-Mobile, $12 million to Sprint, which T-Mobile acquired ‍in 2020; $57 million ​to AT&T ( T ); and nearly $47 million to Verizon Communications ( VZ ).

The fines prompted legal challenges from the companies that eventually led to a split among federal appellate courts over the FCC's in-house enforcement ‍of laws and rules it administers.

The New York-based 2nd U.S. Circuit Court of Appeals upheld the FCC's fine against Verizon. The 2nd Circuit ruled that the Constitution permits the FCC to provide an initial penalty assessment as long as an accused party can challenge the government's collection efforts in court.

That ruling led Verizon to appeal to the Supreme Court.

The New Orleans-based 5th U.S. Circuit Court of Appeals reached a ​different conclusion ‍in a case brought by AT&T ( T ). The 5th Circuit ruled that the FCC's initial assessment of wrongdoing and a fine deprived the company of its constitutional right to a jury ​trial. That ruling prompted the FCC to appeal to the Supreme Court.

The Supreme Court, which has a 6-3 conservative majority, has taken a narrow view of federal agency power in several major decisions in recent years.

The court in 2024 rejected as unconstitutional the Securities and Exchange Commission's in-house enforcement of laws protecting investors against securities fraud. The 6-3 ruling, powered by the court's conservatives, said that agency proceedings seeking penalties for fraud that are handled by the SEC ​itself instead of in federal court violate the Constitution's Seventh Amendment right to a jury trial.

The FCC notched a victory at the Supreme Court in 2025 in a 6-3 ruling that endorsed the way the agency funds its multi-billion-dollar program designed to expand ‍phone and broadband internet access to low-income Americans and other beneficiaries.