New Jersey's State Supreme Court has struck a blow to the increasingly routine practice of law enforcement agencies obtaining cell phone location data from suspects during investigations. In an unanimous 7-0 decision delivered Thursday, the court found that the Middletown Township Police Department violated the state constitution's "right to privacy" when officers obtained a suspect's cell location data from T-Mobile towers in 2006 without a search warrant, during an investigation of a burglary spree. "Individuals have a reasonable expectation of privacy in the location of their cell phones under the State Constitution," the court's ruling explains, also noting: "people do not buy cell phones to serve as tracking devices or reasonably expect them to be used by the government in that way."

"people do not buy cell phones to serve as tracking devices."

Most importantly, the ruling firmly establishes a legal requirement that police in New Jersey need to obtain a search warrant for such data going forward: "This opinion announces a new rule of law by imposing a warrant requirement." However, there's an important caveat that will allow police to obtain some data without a warrant, in the cases of an emergency. Exactly what constitutes an "emergency aid" situation still needs to be established, and the NJ Supreme Court passed that task off to the lower Appellate Court. As the NJ Supreme Court's ruling reads: "If the State can show that a recognized exception to the warrant requirement applies, such as exigent circumstances, then no warrant is needed."

So despite the progress for privacy advocates, the verdict is not a total win for New Jersey residents. Nor will it change national policy. The ruling only applies to New Jersey. And as the State Supreme Court notes: "On a number of occasions, this Court has found that the State Constitution provides greater protection against unreasonable searches and seizures than the Fourth Amendment." At the least, the ruling makes it clear that obtaining cell location data without a warrant should be the exception, not the norm, for police during investigations.