Legal experts say that Wednesday’s landmark Supreme Court decision protecting cell phone privacy does not have any immediate implications for the use of cell tracking devices, known as stingrays. But the court’s ruling could point the way forward for future judicial consideration.

Relatively little is known about how, exactly, stingrays are used by law enforcement agencies nationwide, although new documents have recently been released showing how they have been purchased and used in some limited instances. Worse still, cops have lied to courts about their use. Not only can stingrays be used to determine location, they can also be used to intercept calls and text messages.

Newly published documents show that in July 2008, the Illinois State Police purchased more than $250,000 worth of “covert cellular tracking equipment” from the Harris Corporation, one of the primary manufacturers of stingrays.

“The court's opinion doesn't answer the questions of how courts should approach the use of stingrays or other location tracking, but the court clearly is communicating that the aggregation of our digital data raises acute Fourth Amendment concerns that didn't exist before in the analog age,” Nathan Wessler , an attorney with the American Civil Liberties Union (ACLU), told Ars.

Brian Pascal, a research fellow at the University of California, Hastings, told Ars that he didn’t think that this new ruling would impact metadata gathered via stingrays. “The [Supreme] Court likes to move in small steps, and recognizing that people keep sensitive information on their cell phones is a trivially small step in 2014,” he said. “Stingrays and other forms of dragnet-type surveillance rely, justifiably or not, on the idea that an individual has a reduced expectation of privacy in the metadata attached to their communications. I just don't think this ruling will be taken that far. It's too easy to draw a distinction between, say, sensitive photos and a call history.”

On Wednesday, FBI spokesperson Christopher Allen sent Ars a recent affidavit outlining the agency's position on why so little information has been publicly disclosed.

"The FBI routinely asserts the law enforcement sensitive privilege over cell site simulator equipment because discussion of the capabilities and use of the equipment in court would allow criminal defendants, criminal enterprises, or foreign powers, should they gain access to the items, to determine the FBI’s techniques, procedures, limitations, and capabilities in this area," Bradley Morrison, chief of the Tracking Technology Unit at the FBI, stated in the affidavit. "This knowledge could easily lead to the development and employment of countermeasures to FBI tools and investigative techniques by subjects of investigations and completely disarm law enforcement’s ability to obtain technology-based surveillance data in criminal investigations."

Third-party doctrine strikes again

The Supreme Court ruled unanimously not only in these cases (and), but also in the case of United States v. Jones , the notable 2012 case finding that law enforcement does not have the right to warrantlessly place a GPS tracking device on a target vehicle.

Still, some noted that lower courts would likely look to this Supreme Court decision as a means to evaluate the legality of stingrays and other forms of digital surveillance.

“As a technical matter, I don't see the case as having any direct impact on stingray or other surveillance issues other than searches of cell phone incident to arrest,” Fred Cate, a law professor at Indiana University, told Ars. “But as a practical matter, the Supreme Court has said 9-0 that it has joined the 21st century and the majority of citizens in recognizing that new technologies present new challenges to privacy and that the Constitution must be read to protect privacy even in the face of new technological challenges. Law enforcement officials would be crazy to ignore that message, and even if they do, lower courts will not.”

In Riley, the court specifically cited a 1979 Supreme Court decision, (Smith v. Maryland) which firmly established the so-called “third-party doctrine.” In the United States, this legal principle says that individuals have no reasonable expectation of privacy over information already disclosed to a third party, such as a number dialed. Therefore, the government has argued, authorities can access that information without a warrant.

The third-party doctrine has been used beyond ordinary criminal cases as well. In 2013, the Foreign Intelligence Surveillance Court (FISC) found that if the transfer of one person’s information is legal, so too is a wholesale, en masse transfer of such data. Therefore, the FISC reasoned, the National Security Agency's metadata handover program (the first secret program revealed by documents originating from the Edward Snowden leaks) is legal.

“Necessary to reconsider”

In Wednesday’s decision, the Supreme Court said that it rejected the government’s argument that the police’s search of Wurie’s phone was authorized.

The Government relies on Smith v. Maryland, 442 U. S. 735 (1979), which held that no warrant was required to use a pen register at telephone company premises to identify numbers dialed by a particular caller. The Court in that case, however, concluded that the use of a pen register was not a “search” at all under the Fourth Amendment. See id., at 745–746. There is no dispute here that the officers engaged in a search of Wurie’s cell phone. Moreover, call logs typically contain more than just phone numbers; they include any identifying information that an individual might add, such as the label “my house” in Wurie’s case.

Hanni Fakhoury, an attorney at the Electronic Frontier Foundation said that this section of the decision is notable. “That paragraph suggests that it's not necessarily the phone number itself that lacks constitutional protection, but rather the means by which the government gets the record may not trigger constitutional protections,” he said. “In Smith, the cops got the info from the phone company. But in Wurie/Riley, they’re getting the info from the phone itself, and that’s a ‘search.’ So with a stingray, although it's only technically capturing phone ‘routing’ information, the fact the police are operating the stingray directly and getting the records themselves rather than getting them from the phone company may trigger different Fourth Amendment interests. So I’d expect to see renewed legal challenges to the use of a stingray once people can actually figure out if one was used in their particular case.”

Brian Owsley, a former US magistrate judge, agreed with this analysis. "The Court rejected the government's citation of Smith in support of its arguments that cell phone logs are unprotected by the Fourth Amendment," he said. "That is a step that at a minimum reduces the impact of Smith. Ultimately, the Court holds that information on a cell phone is protected by the Fourth Amendment. I think that information should include outgoing cell phone numbers as well as the other information available by using a pen register."

Some of the justices, notably Justice Sonia Sotomayor, seemed to indicate in the 2012 Jones decision that they may be amenable to reviewing the entire third-party doctrine. “More fundamentally, it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties,” she wrote.

Still, Wessler, the ACLU attorney, said he is hopeful.

“While the court hasn't settled those issues, lower courts will look to the logic of those opinions to assess what kind of privacy protections we need for other forms of persistent digital monitoring,” he said. “Wurie doesn't say anything about NSA spying or any of the other issues, but this is yet another example of the court taking very seriously what our privacy rights should be in the 21st century. The court got it right in Jones, and they got it right here, because the justices understand that the large-scale access to data raises new issues that need more robust protection.”