Law professor and author Arthur Miller, appearing as an expert in civil procedure Thursday, agreed with the National Rifle Association's argument that the New York Attorney General's Office cannot prevent the gun-rights group from reviewing potentially privileged material in the possession of its former advertising agency Ackerman McQueen, which has received a state subpoena.

The subpoena is related to the Attorney General's Office's ongoing investigation into the NRA and its financial affairs, which was publicly confirmed in April.

In an October hearing, lawyers with Brewer, Attorneys & Counselors, which is representing the gun rights advocacy group, argued that the NRA had a special relationship with Ackerman that went beyond standard ad agency work. Ackerman routinely received legal advice from NRA attorneys, the lawyers said, and the agency may also possess the names of NRA donors.