The New Jersey Supreme Court ruled on July 18, 2013 in State v. Thomas W. Earls that the police will have to obtain a search warrant to obtain location information from cell phone providers.  Cell phone providers can place the location of cell phones at specific times by tracking the particular cell phone tower with which the cell phone is interacting or has interacted in the past.  Typically, law enforcement agencies have been able to obtain this data without a warrant in other parts of the country.  

The Court based the ruling on the expectation of privacy reasonably expected by cell phone customers.  The decision was based squarely on the New Jersey State Constitution guarantees of privacy and not the Fourth Amendment to the U.S. Constitution, which protects against unreasonable searches and seizures.