Professor Lilly was appointed teaching assistant at Catholic University School of Law in Washington, D.C., for two years, before serving as law clerk to Judge Edmund L. Palmieri, U.S. District Court for the Southern District of New York. He practiced tax law in Manhattan while earning the Master of Laws degree in Taxation at New York University School of Law. He has taught summer courses at the University of San Diego School of Law.

Federal taxation, business organization and finance, and international business.