This document defines and discusses the Islamic legal principle of istislah (considering public interest and benefit). Istislah involves deriving rulings to acquire benefits and prevent harms for the public where the sacred texts are silent. It defines types of maslahah (public interests) and categories of istislah based on the strength of textual support. The document outlines majority and minority views on when istislah can and cannot be applied and provides examples of its use historically and in modern times.