On the Rules of Law

Bulgarus was a prominent jurist in the 12th century and a key figure at the University of Bologna, a center for the study of Roman law. He was one of the "four doctors" of law and is believed to have been a student of Irnerius. Bulgarus's work, particularly his treatise De regulis iuris (On the Rules of Law), is the earliest surviving legal gloss from the Bolognese school. This work is significant because it represents an adherence to the letter of the law, contrasting with the more equitable approach favored by his contemporary, Martinus Gosia. Bulgarus's legal interpretations ultimately prevailed and influenced the development of medieval law. The "rule of law" itself refers to a system where laws are obeyed by everyone, preventing arbitrary use of power.123