The primary objective of this article is to trace the origin, history, and development of the legal device of public interest in Islamic law. How did this idea of public interest come about? Do the primary sources of Islamic law talk about the public welfare and public interest in any technical term? How did classical Islamic scholars contrive the idea of the public interest in Islamic law? what are the limits and parameters of the legal device of the public interest in Islamic law? why do some Salafi groups do not recognize the legal device of Islamic law? I will trace the arguments of the proponents and opponents of the legal device of public interest in Islamic law.