"Courts are all over the place on all of these issues," said Hanni Fakhoury, an attorney with the Electronic Frontier Foundation, a privacy group.
Among the questions being confronted: Should GPS evidence gathered before the 2012 decision be admissible in court? What are the rights of a passenger in a car being tracked by GPS? And how might the ruling affect other types of technology, such as pole-camera surveillance and "Stingray" devices that capture cellphone data?
That ambiguity was on display just last week, when an Atlanta-based federal appeals court ruled in the case of a man imprisoned for armed robberies that investigators need a warrant to get cellphone tower tracking data, evidence authorities use to place suspects in the vicinity of a crime. Yet an appeals court in New Orleans last year authorized warrantless cell site tracking in a case that presented similar legal issues. A related federal case in Michigan is now on appeal, too.
The questions form a broader debate about how police should confront "circumstances of legal ambiguity," said former federal prosecutor Caleb Mason, who has written on the Jones case.
"Do we want them pushing the envelope as long as no legal authority, no appellate court, has expressly told them no?" he asked.
Against the backdrop of a high-tech world, the justices deciding the Jones case grappled with fundamental principles of privacy and trespass that have been drawn on repeatedly in similar surveillance disputes.
The court held that police erred when, without a valid warrant, they attached a GPS tracking device to the Jeep of a Washington, D.C., nightclub owner. The surveillance continued for a month, leading authorities to a stash house for drugs and helping secure an indictment against the suspect, Antoine Jones.
The justices unanimously agreed that using the device constituted a search under the Fourth Amendment, which bars unreasonable searches and seizures. But they stopped short of saying a warrant is always required an important point since not all searches require warrants and produced three separate opinions offering different legal explanations for their views. Several justices mused at the time that the issues probably would resurface.
One, Samuel Alito, wrote that technological change can alter the public's expectation of privacy and that lawmakers may be better suited than judges to account for the changes. Another, Sonia Sotomayor, also discussed privacy concerns in the digital age in her separate opinion.
The Justice Department, too, has wrestled with the case's outcome.
An internal department memo issued after the case was decided noted that the "case potentially has far greater implications" than just GPS tracking. It advises federal agents and prosecutors as a matter of course to get a warrant for GPS evidence "to minimize litigation risk."
In investigations where warrantless GPS evidence was obtained before the case was decided, the memo says, prosecutors may reasonably argue that the evidence should be admitted provided that the officers were acting in good faith based on their understanding of the law at the time.
Spokesman Peter Carr said last week that it was department policy to obtain a search warrant to use any technology in locations where an individual had a reasonable expectation of privacy.
Some courts have agreed that warrantless GPS tracking prior to the Jones case was acceptable, though that idea isn't universally accepted.
In throwing out evidence against three brothers charged in a wave of pharmacy burglaries, a three-judge panel of the 3rd U.S. Circuit Court of Appeals ruled last year that police were required to get a warrant before using a GPS device in 2010, rejecting prosecutors' "good faith" argument. The entire court reheard the case May 28.
Courts have been similarly divided on whether car passengers, or nonowners, have legal authority to challenge GPS evidence against them.
The Jones decision has also been invoked in court disputes over the NSA's telephone records collection. A federal judge in Washington cited the opinions of Alito and Sotomayor in the Jones case to find that telephone users have a reasonable expectation of privacy and to declare the NSA program likely unconstitutional. A federal judge in New York rejected a plea from civil libertarians to invoke those same opinions and instead upheld the NSA program.
Police and judges also are wrestling with the privacy implications of other modern forms of surveillance. In Washington state, for example, privacy advocates are arguing that the Jones case requires a court to throw out warrantless video surveillance captured by a pole camera left by police for a month outside a defendant's house in a drugs and weapons case.
In one way or another, the questions will likely come before the Supreme Court again, said Brian Hauss, an American Civil Liberties Union lawyer. Police should have clear rules that apply across multiple technologies, he said.
"Right now, they're operating in an area of total confusion without significant judicial checks on their authority."