Practising Law Institute (PLI) | 13,138 followers on LinkedIn. A nonprofit learning organization dedicated to keeping legal professionals at the forefront of knowledge and expertise. | Practising Law Institute is a nonprofit learning organization dedicated to keeping attorneys and other professionals at the forefront of knowledge and expertise. PLI is chartered by the Regents of the University of the State of New York, and was founded in 1933 by Harold P. Seligson.