Seinfeld's recent scholarly work explores the role of national unity in shaping the contours of our constitutional law. Prior to joining the faculty, Seinfeld was an associate at the law firm of Wilmer Cutler Pickering Hale & Dorr, where he focused on appellate litigation. In between his clerkships, he was a fellow in the Program in Law and Public Affairs at Princeton University. In 2006, he was the recipient of the Law School's L. Hart Wright Award for Excellence in Teaching. His scholarly work has been published in numerous law reviews, including the Michigan Law Review, the University of Pennsylvania Law Review, and the California Law Review. He is admitted to practice in New York.