According to the Supreme Court, a warrant is necessary to access a cellphone's location history. This is considered a major victory for the privacy rights of Maryland residents and all Americans. Its 5-4 decision in Carpenter v. United States is also seen as widening the scope and updating the Fourth Amendment. Under the Stored Communications Act, police could obtain cell site location information, or CSLI, as long as it could reasonably be used to find data relevant to an investigation.
The Carpenter case involved a man who had been taken into custody based on 127 days of cellphone location data. He argued that the data allowed authorities to violate his privacy in ways that were not available in times before cellphones. Therefore, the third-party doctrine usually used by the court should not apply in this case. Chief Justice Roberts agreed with the four liberal justices that a person has an expectation to privacy as it relates to CSLI.
Those who dissented generally claimed that individuals don't have a right to privacy as it relates to information turned over to a third party. All four justices who dissented in the case wrote their own opinions in the matter. Justice Alito specifically claimed that the court had erred in changing the basis of the Fourth Amendment to accommodate a new technology.
Whether an individual is facing a felony or misdemeanor conviction, it may be a good idea to consult with an attorney. Legal counsel may create a defense to the charge that might result in a case being thrown out or resolved through a plea bargain. For example, it may be possible to argue that a person's right to privacy was violated, rendering evidence collected in the case inadmissible.