The Supreme Judicial Court quashed a Grand Jury subpoena approved by a Suffolk Superior Court judge that required Aaron Hernandez’s defense lawyers to turn over his cellphone, the Boston Herald reports. According to the SJC, the subpoena was an attempt by prosecutors to misuse the Grand Jury to obtain evidence in the double homicide prosecution, rather than using the proper channels to obtain a valid warrant.

The authority and function of the Grand Jury is derived from the Fifth Amendment, and is regulated in Massachusetts by Mass. Rule of Criminal Procedure 5. The Grand Jury serves an entirely different function than the better known trial jury, also known as the “petit” jury because of its smaller size. In contrast to the petit jury that actually observes a trial and renders a verdict on either a criminal or civil case, the Grand Jury’s sole function is to investigate a crime at the direction of the prosecutor, and to determine whether the alleged suspect likely committed the crime (probable cause).

There are three more important distinctions between the Grand Jury and the petit/trial jury. First, the Grand Jury only hears from the prosecutor, and the witnesses which either the prosecutor presents or the Grand Jury summons. There is no judge, and no defense attorney present. Second, the identity of the Grand Jurors and the evidence presented in a Grand Jury are completely secret throughout the length of each Grand Jury. Only the prosecutor and any testifying witnesses could know what is said in a Grand Jury proceeding. The last important distinction is the investigative power wielded by the Grand Jury, the exercise of which triggered this SJC decision.

As part of its investigative function, the law allows a Grand Jury the power to compel witnesses to testify on the record to answer its questions, as well as the power to compel witnesses or third parties to disclose information pertinent to the investigation. This power, however, is limited by certain rules, such as the attorney-client privilege. In Hernandez’s case, the Suffolk County Grand Jury issued a subpoena for Hernandez’s cell phone, which Hernandez had already delivered to his lawyers for safekeeping. Suffolk County prosecutors asked the trial court to order the surrender of the cell phone at the Grand Jury’s request, because the cell phone’s content was believed to be pertinent to the double homicide.

Though the Suffolk judge approved the subpoena, the SJC granted the defense team’s appeal and essentially quashed the subpoena. Though the SJC’s decision is impounded (unavailable to the public), the Boston Herald reports that the SJC found the prosecutor to be attempting to misuse the Grand Jury to request a search of a cell phone that the prosecutor would not otherwise have access to. The SJC explained that because the cell phone was already in the defense attorneys’ possession, it was protected by the attorney-client privilege, and so the defense attorneys had an ethical and legal duty to protect that property for their client. If the prosecutor wants access to the phone, he will need to obtain a valid search warrant.