1088 is widely considered the date in which free teaching began in Bologna, independently from the ecclesiastic schools. At the end of the 11th century, masters of grammar, rhetoric and logic began to apply themselves to law in Bologna, and the earliest recorded scholar was a man named Irnerius, whose activities cataloguing the Roman legal materials soon ran beyond the boundaries of Bologna.
Right from the outset, the students paid the teachers a "collectio", as a gift rather than a salary, as at that time science, a gift of God, could not be sold. Gradually such donations were transformed into actual salaries. In any case, the students did not always give to the collectio, and the municipality had to intervene to allow the studies to continue.
Between the 11th and 12th centuries came the Investiture Controversy. It was a fundamental period for the development of European politics, defining the relations between the State and the Church. During the controversy, debates on law were fundamental, and equally so was the study of the Codex Justinianus, the foundation of the Empire identity. In 1158 four experts in law, four "doctores" deemed to be the pupils of Irnerio, Bulgaro, Martino, Jacopo and Ugo di Porta Ravegnana were invited by Frederick I Barbarossa to the Diet of Roncaglia to express their opinion on the laws of the Empire compared to those of other political bodies. With the exception of Martino, the other three declared themselves in favour of the Empire. They demonstrated with very fine explanations that the only Law was Roman Law, entrusted to the Empire. Consequently, in 1158 Frederick I Barbarossa promulgated a Constitutio Habita, establishing that every school be established as a "societas di socii" (group of students) overseen by a master (dominus) remunerated by the sums paid to him by the students. The Empire undertook to protect scholars travelling for the purpose of study from the intrusion of all political authorities. This was a fundamental event in the history of European university. The University was legally declared a place where research could develop independently from any other power.
http://www.unibo.it/en/university/who-we-are/our-history/university-from-12th-to-20th-century