Complex sentence: It was around that time that Hadrian enacted, through the jurist Salvius Julianus, what was to become the first attempt to codify Roman law: the Perpetual Edict, according to which the various forms of legal action introduced yearly by pretors were to remain fixed.
Split into simpler sentences: It was around that time that Hadrian enacted, through the jurist Salvius Julianus, what was to become the first attempt to codify Roman law. This was the Perpetual Edict, according to which the various forms of legal action introduced yearly by praetors were to remain fixed.