Baltimore is scarcely alone — New York’s Erie County has admitted similar behavior. Judges and defendants were either not notified or the police sought simple pen register approval. A pen register is a device ruled constitutional in the 1979 case Smith v. Maryland — it gathers information about which phone numbers have been dialed by a specific telephone line, but records no other data.
In the 15 years since the Patriot Act, much of the expansion of government power has been based on the argument that individuals consent to tracking through their use of certain services. This argument hasn’t been unilaterally accepted at the Supreme Court, but it’s still been used to justify the widespread deployment of so-called stingrays — devices that simulate a cell phone tower and can gather large amounts of information by forcing cell phones to connect to it.
Maryland’s Special Court of Appeals pushed back against this trend this week, when it upheld a lower court ruling that suppressed evidence gathered by a stingray. That’s particularly significant because Baltimore police testified in court that they had deployed stingrays a jaw-dropping 4700 times since 2007.
In this specific case, Keron v. Andrews, the police applied for a pen register tap while gathering information about a potential murder suspect. Instead, they deployed a type of stingray dubbed Hailstorm. In the court transcript, Baltimore detectives testify that Hailstorm is a second-generation type of device, whereas the term “Stingray” referred to an older, less-capable product.
The Supreme Court ruled that using a thermal imaging camera was unconstitutional because the police didn’t have a warrant authorizing the search at the time they used it. Justice Scalia, writing for the majority, argued that the Fourth Amendment created a “firm but also bright” line at the “entrance of the house.” The use of a stingray to find and lock on to a mobile phone, it could be argued, is a similar violation of this bright line that would also trigger Fourth Amendment protections. To date, the Supreme Court has not taken up this issue.
One reason this case has been viewed as significant is because of a brief filed by the state attorney general of Maryland. In that brief, the government argued that by simply owning a cell phone and keeping it powered, the defendant was “voluntarily sharing the location of his cell phone with third parties.”
The Maryland Court of Special Appeals upheld the ruling throwing out the evidence gathered by police because they agreed that the pen register application was a “completely false document” and “completely disingenuous.” There is, however, another potential argument to be made on Fourth Amendment grounds. In Kyllo v. United States, the Supreme Court ruled 5-4 that the police had violated the Fourth Amendment rights of the defendant when they used a FLIR thermal imaging camera to measure the amount of heat radiating from a home. Once the police had measured unusual amounts of thermal radiation, they used this information to justify a search warrant. Kyllo, the defendant, was found to have more than 100 marijuana plants growing in his home, and was subsequently arrested.