The Allegheny County Law Library is the only public law library in Allegheny County. It has been serving the community and the court system for over 150 years.

In 1867, Act No. 1211 provided for the purchase and support of a county law library, to be kept in, or near, the courthouse for the use of area citizens.

Percy Digby was the first library director, serving from 1885 to 1907. Today, the Allegheny County Law Library is managed by Carnegie Library of Pittsburgh through a unique partnership with Allegheny County.