Mandatory criminal penalties are basic to any penal code. Like other criminal systems, Islamic jurisprudence does prescribe certain punishments in certain situations, but any criminal judgement must be carried out by a state authority, as Islam does not allow vigilantism. Furthermore, most of these punishments were meant to act as deterrents, and, in practice, the most severe punishments were rarely carried out.
For instance, the punishment of stoning for adultery requires the testimony of four eyewitnesses—a virtually impossible condition. Capital punishment for manslaughter could be avoided if the victim’s family agreed to monetary compensation for their loss—a normal practice in the society of the time.
These punishments are very similar to those found in the Hebrew Bible, which, like the Qur’an, spoke to social conditions and attitudes vastly different from those of later times and different places. Jews today, even the most strictly Orthodox, do not practice these punishments, and Christians generally regard them as superseded by the ethic of Jesus.
Today, most Muslim-majority countries do not practice these punishments, and where they are practiced, such as under the Taliban or ISIS, the required due process that makes many of these punishments nearly impossible to enforce is not followed, which is why many scholars have condemned their use.