The history of Roman law can be divided into three systems of procedure: that of legis actiones, the formulary system, and cognitio extra ordinem. Though the periods in which these systems were in use overlapped one another and did not have definitive breaks, the legis actio system prevailed from the time of the XII Tables (c. 450 BC) until about the end of the 2nd century BC, the formulary procedure was primarily used from the last century of the Republic until the end of the classical period (c. AD 200), and cognitio extra ordinem was in use in post-classical times.
