The police originally got authority to use a "D-Order", which allows them to gather records and is easier to obtain than a subpoena. In Judge Sentell's opinion paper, he notes, that the police effectively did an end-run around typical requests for this information. Choosing to treat the request as on-going investigative data instead of the precedent set in previous cases. The judge goes on to say, "...it cannot be denied that the Fourth Amendment protection against unreasonable searches and seizures shields the people from the warrantless interception of electronic data or sound waves carrying communications." His follow-on argument suggests that by using the location information the police gathered and the manner in which they gathered it is effectively monitoring an individual, which does require a warrant.
Davis was still found guilty, but the court effectively put law-enforcement on notice about the manner in which is obtains this data for future cases."
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