This document discusses the Islamic legal principle of sadd al-dhara'i' (blocking the means). It defines sadd al-dhara'i' as blocking the means to an expected evil end to prevent it from materializing. Means can be blocked if they are likely or certain to lead to an unlawful result. The document provides examples from the Quran, hadiths, and rulings of early jurists to illustrate different types of means and when they can be prohibited. It also discusses contemporary issues where the principle could apply, like regulating internet use or banning fireworks to prevent harm.