Professor Trains Supervising Prosecutors through National Institute for Trial Advocacy June 17, 2010 ÌýProfessor Gwen SternÌýtrained supervisors in the Philadelphia Office of the District Attorney on June 11-12. As an instructor with the National Institute for Trial Advocacy, Stern taught supervisors how to train and groom newly minted district attorneys. Stern directs the law school’sÌýTrial Advocacy Program as well as the Marshall-Brennan Constitutional Literacy Project.