المصالح المرسلة
al-Maṣāliḥ al-mursalah
Public welfare on which no source gives a ruling, taken by some jurists as a basis of Islamic law.
What it means
Maṣlaḥah means benefit or public interest, and mursalah means “left free”, that is, not tied to a particular text. The term names a benefit for which the Quran and the Sunnah give neither a command nor a prohibition. Many jurists, and especially the Maliki school, allow rulings based on such benefit where it serves the aims of the law and harms no one.
Examples often cited are the gathering of the Quran into one volume under Abu Bakr and Uthman and the state registers set up by Umar, which no text commanded but which served the community. The jurists set conditions: the benefit must be real and general, and it must not contradict any text. Al-Ghazali accepted it in this limited way, and it is related to the wider theory of the purposes of the law, and later jurists such as al-Shatibi built on it.
Often misunderstood as
It is sometimes treated as a licence to follow whatever seems useful, though jurists limited it by conditions and by the texts of revelation.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 52, listed as AL MAṢĀLIḤ AL MURSALAH. The definition is restated here.