This decree established by the Abbasid caliph, al-Ṭāʾiʿ li-Allāh (r. 974-991) establishes the role of the Ṣāḥib al-Maẓālim as different from that of the judge. The Ṣāḥib, or officer, is tasked with investigating complaints of injustice in situations where the executive power must intervene. In this capacity he can search “for types of evidence that are obscure and concealed.” In contrast, the judge must rely only on “solid and plain evidence.”