The Maryland Court of Special Appeals ruled yesterday that the state Human Relations Commission may not use its subpoena power to gain police documents when it is investigating police brutality allegations.

The ruling came in a case in which the commission attempted to investigate an April 1976 melee involving Prince George's County police that began when a man was stopped for running a red light in Glenarden.

The commission first asked for, then subpoenaed arrest reports and other documents relating to the incident. When the police department failed to turn them over, the commission sought and won a Prince George's County Circuit Court ruling ordering the department to comply with the subpoena.

The department appealed, and yesterday in a decision written by Chief Judge Richard P. Gilbert, the special appeals court reversed the Circuit Court ruling. Gilbert ruled that the "commission's authority is not boundless, and that its thrust is directed toward three principal areas: public accommodations, housing and employment."

The commission may use its subpoena power in these areas, but is prohibited from using it in a police investigation because such probes are governed by a separate state law, according to the opinion.

The opinion still allows the commission to investigate police harassment complaints, as long as it does not subpoena police documents.

The April 11, 1976, melee ended with the arrest of five civilians and with six police officers and several civilians being treated for injuries according to reports of police and citizens. Police Chief John Rhoads later said the events "failed to reveal specifics and evidence that support disciplinary action" against the officers involved.