The Appellate Division Law Library for the 4th Department was established in 1849 and has a long and distinguished history. The Library actually pre-dates the court for which it is currently named by almost fifty years. As the Library approaches its 160th anniversary, it continues to rank among the largest court libraries in the nation. The Fourth Department consists of the counties within the Fifth (Jefferson, Lewis, Oswego, Oneida, Herkimer, and Onondaga counties), Seventh (Monroe, Wayne, Ontario, Seneca, Cayuga, Yates, Livingston, and Steuben Counties), and Eighth (Niagra, Orleans, Genesee, Erie, Wyoming, Chataugua, Cattaraugus, and Allegany Counties) Judicial Districts - twenty-two western New York counties stretching westward from the Adirondack Mountains to Lake Erie.
Appellate Division Fourth Department Law Library is a member of the Rochester Regional Library Council.