Professor Hartnett is the Richard J. Hughes Professor for Constitutional and Public Law and Service at Seton Hall University School of Law, where he teaches Constitutional Law, Civil Procedure, and Federal Courts.  He has also pioneered a course in opinion drafting, in which students work from documents filed in actual cases in United States District Court.  

He is co-author of Supreme Court Practice, commonly known as Stern & Gressman, the bible for anyone handling a case at the Supreme Court.  He has published articles in journals including Columbia Law Review, Constitutional Commentary, Duke Law Journal, Fordham Law Review, Michigan Law Review, NYU Law Review, Notre Dame Law Review, University of Pennsylvania Law Review, Texas Law Review, and William & Mary Law Review. 

After graduating from Harvard College and New York University School of Law, he clerked for United States District Judge Frederick B. Lacey, United States District Judge Robert E. Cowen, and United States Chief Circuit Judge John J. Gibbons.  He was an Assistant Federal Defender and an associate at Robinson, St. John & Wayne, before joining the faculty at Seton Hall in 1992.  He has been a visiting professor at the University of Virginia and the University of Pennsylvania, and a scholar in residence at St. Peter's College and Cardozo Law School.