Adl, as used by early theorists of Islamic jurisprudence, referred to an aspect of an individual's character. This aspect is best translated as probity. Although Adl, as used by many religious scholars today, is loosely used as meaning solely justice, one must look more closely at how and why religious scholars choose to use this word.
Adl is another word for divine justice in Islam. The conception of this term varies between Shias and Sunnis. Shias tend to believe that God is rationally just, that men inherently know the difference between good and evil, and that we have complete free will. Sunnis, in contrast, believe that God is necessarily just, that revelation, the Qur'an, is the only way to know good and evil, and that men are afforded some volition within predestination.
The origin of the modern family name Adl is from the titles of nobility given to Iranian jurists at the end of the 19th century, that were related by family ties. Notably, these jurists included Hajj Mirza Hossein (also known as Hossein Shah) whose title was Adl-ol-molk (Justice of the Kingdom), Seid Mirza Ebrahim Khalil whose title was Rokn-ol-edaleh (Pillar of Justice), and Mirza Mostafa Khan Adl whose title was Mansoor-ol-saltaneh (the Victorious of the Empire). The latter, Mostafa Adl, drafted Iran's modern civil code (hoghough-e-madani) shortly after the Iranian Revolution of 1903–1905, which was enacted by the then parliament and is still being used today by the present regime.