NEW YORK -- A New York federal appeals court added its voice Friday to a growing chorus of rulings defining when a GPS device can be used to track a criminal suspect, refusing to toss out evidence gathered without a warrant in a Vermont drug case.

The 2nd U.S. Circuit Court of Appeals in Manhattan upheld the convictions of three men arrested after Burlington police pursued a drug ring suspected of transporting cocaine from Massachusetts to Vermont. It said the federal Drug Enforcement Administration agent who attached the device to the vehicle acted constitutionally, because investigators had probable cause to believe the car was being used to commit a crime.

The decision came in an area of law that is still being defined even as global positioning system devices are increasingly used as an investigation tool.

The ruling also came a day after the 3rd U.S. Circuit Court of Appeals in Philadelphia announced that its full appeals court will hear a case about whether police need a warrant to attach a GPS device to a suspect’s vehicle. A three-judge panel concluded in October that police needed a warrant, though that ruling was vacated when the full court decided to take up the case.

Some of the confusion over how to interpret the law stems from a January 2012 U.S. Supreme Court ruling that established that the government’s installation of a GPS device on a vehicle constitutes a "search" within the meaning of the Fourth Amendment’s protections against unreasonable search and seizure.

At the time, Justice Sonia Sotomayor wrote in a separate opinion that it may be time to rethink all police use of tracking technology, not just long-term GPS.

"GPS monitoring generates a precise, comprehensive record of a person’s public movement that reflects a wealth of detail about her familial, political, religious and sexual associations," Sotomayor said. "The government can store such records and efficiently mine them for information for years to come."

The 2nd Circuit said the Supreme Court settled the issue of whether a GPS device constitutes a search but did not address whether the warrantless use of GPS devices would be reasonable and lawful when officers have reasonable suspicion and probable cause to conduct such a search.

Regardless, the 2nd Circuit three-judge panel said law as it existed during the Vermont investigation made it reasonable for investigators to believe they were acting legally in placing a GPS device on a vehicle rather than following the vehicle around as they would have had to do in the past.

"At bottom, sufficient Supreme Court precedent existed at the time the GPS device was placed for the officers here to reasonably conclude a warrant was not necessary," the court wrote. It added, however, that in light of the Supreme Court ruling, "the landscape has changed, and law enforcement will need to change its approach accordingly."