Antonio Negri is professor of Theory of the State at the University of Padua. Negri actively collaborated in the debates and struggles of workers of the Italian radical left during the 1960s and 1970s. He participated in the publication of the Quaderni Rossi, Classe operaia and La classe, and was part of the non-parliamentary group Potere Operaio. Negri was an active organizer and leading theorist in the debate around worker autonomy, and has taught at some of the most important universities in Europe. Upon being arrested in 1979, he spent more than four years in prison and lived in exile in France from 1983–97. After returning to Italy and following another period of incarceration of almost six years, he now lives in freedom. He is the author of more than twenty books. Together with Michael Hardt, he is the author of the celebrated trilogy Empire (2001), Multitude: War and Democracy in the Age of Empire (2005), and Commonwealth (2009).