The essay intends to reconstruct the facts concerning the assassination attempt conceived, but never put in action, by the anarchist Michele Schirru against Benito Mussolini. Schirru was arrested in Rome on 3 February 1931, confessed the will to hit Mussolini, was sentenced to death and shot in Forte Braschi, in Rome, on 29 May 1931. The Schirru’s Case is historically relevant also because it is tied with a basic change in the istitutional structure of the Fascist State. The new Italian Penal Code, also known as Codice Rocco, which included exceptional laws concerning the crimes against the Duce, came in force in June 1931, just few days after Schirru’s death. The anarchist’s trial served well to solve some juridical matters both from the doctrinal and jurisprudential: point of view, as the precise statement of the notions of attentato (failed outrage) and tentativo (attempt), going beyond the distiction between preliminary and executory acts, and the specification of the concepts of crime esecutività (enforceability), idoneità (suitability) and univocità (univocity).