What are the Sharia requirements that must be met by the four witnesses to file a lawsuit in an Islamic court, and what is their purpose?

The conditions for testimony in Islamic jurisprudence vary according to the matter being testified to. Some matters accept the testimony of one just witness (such as sighting the Ramadan crescent), some require two witnesses (such as marriage, divorce, and retribution), and some require four witnesses (such as adultery).

For testimony of adultery, four male witnesses are required. They must describe the observation with extreme precision that leaves no room for interpretation, such such as the penetration of the male organ into the female organ. Merely seeing a man and a woman together is not sufficient. This strictness in the conditions for testifying to adultery aims to protect honor and prevent leniency in slandering people, making the establishment of the hadd punishment for adultery by testimony very rare. The punishment is often established by confession or the presence of pregnancy.