Political scientist with specialization in public administration and the analysis of judicial systems, with special emphasis on comparative studies. He has analyzed in depth the characters of judicial guarantees of independence, their main traits and their evolution. A similar attention has been devoted to the status and role of public prosecution and to the principle of compulsory prosecution. More recently, his interests have focused on the process of judicialization of politics - that is, the expansion of judicial power - with specific attention to Italy and Europe and on the increasing significance of supranational and transnational justice for national courts. Beside university teaching, he has extensively participated to judicial training, especially at the Belgian, French, Italian and Spanish judicial schools.