The doctrine of adl took its classical shape among the Mutazila, a rationalist theological school that rose in Basra and Baghdad in the eighth century and dominated Abbasid court theology for a time under caliphs including al-Ma'mun. The Mutazila organized their system around five principles, al-usul al-khamsa: the oneness of God, tawhid, understood in a way that denied any eternal divine attribute distinct from His essence; divine justice, al-adl, understood to mean that God is bound by the same standards of right and wrong that reason can discover on its own, and therefore cannot decree evil, deceive His creatures or punish the innocent; the promise and the threat, that God's stated rewards and punishments in the afterlife must occur exactly as promised; the intermediate position, that a Muslim who commits a grave sin is neither a believer nor an unbeliever but occupies a status between the two; and commanding right and forbidding wrong, treated as a binding communal duty.
Sunni traditionalist and later Ash'ari theology pushed back hard against the justice principle specifically, regarding it as subjecting God to an external standard, and Mutazili influence receded sharply in Sunni intellectual life after the tenth century, though it left a lasting mark on Twelver Shia theology, which absorbed several of its central commitments and still teaches them today.