- J. Scott Marcus is a Senior Fellow at Bruegel, a Brussels-based economics think tank, and also works as an independent consultant dealing with policy and regulatory policy regarding electronic communications. His work is interdisciplinary and entails economics, political science / public administration, policy analysis, and engineering.
- J. Scott Marcus is a member of the Scientific Committee of the Communications and Media program at the Florence School of Regulation (FSR), a unit of the European University Institute (EUI).
- He is also a Fellow of GLOCOM (the Center for Global Communications, a research institute of the International University of Japan).
- He is a Senior Member of the IEEE; has served as co-editor for public policy and regulation for IEEE Communications Magazine; served on the Meetings and Conference Board of the IEEE Communications Society from 2001 through 2005; and was Vice Chair and then Acting Chair of IEEE CNOM.
- He served on the board of the American Registry of Internet Numbers (ARIN) from 2000 to 2002.