Maryland Code, Criminal Procedure § 15-108

(a)(1) For the limited purpose of furthering an ongoing criminal investigation, a State's Attorney or a deputy State's Attorney designated in writing by the State's Attorney may issue in the county served by the State's Attorney a subpoena to a person to produce telephone, business, governmental, or corporate records or documents.

(2) The subpoena may be served in the same manner as one issued by a circuit court.

(b)(1) A person may have an attorney present during any contact made under subsection (a) of this section with a State's Attorney or an agent of the State's Attorney.

(2) The State's Attorney shall advise a person of the right to counsel when the subpoena is served.

(2) After conducting a hearing at which the person who allegedly failed to comply with a subpoena issued under subsection (a) of this section has an opportunity to be heard and represented by counsel, the court may grant appropriate relief.