[3] Cassinis entered the chambers of the famous lawyer Prigione and established a name for himself in the theoretical analysis of law, publishing dissertations on the death penalty and the rights of the church.

[3][4] Cassinis' political career began in his region of origin, first as a municipal councillor in his native Masserano in 1848,[5] then as representative of the Salussola constituency in the first legislature of the Subalpine Parliament.

The first, appointed by Farini in November 1859 for the provinces of Emilia and the other established in Turin in December by Rattazzi and composed of Piedmontese and Lombard jurists.

The new commission, in which some Tuscan jurists to ensure representation to all parts of the expanding Kingdom of Italy, worked extremely quickly on the revision of the Albertine code.

[6] In October of the same year he assumed the position of Minister of the Interior, a role which led him to carry out a long mission in southern Italy aimed at accelerating the national unification procedure.