THE TALIBAN plans to rule Afghanistan in accordance with sharia law. During its previous stint in power, the militant group was known for its strict interpretation of Islamic jurisprudence, banning music and forcing women to wear a full burqa in public. But many countries besides Afghanistan—among them Saudi Arabia, Iran and parts of Indonesia and Nigeria—also use sharia law without such strictures. So what is sharia, and how is it applied?

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Sharia means “path” in Arabic, indicating the conduct that pleases God. It covers criminal, commercial and family law but is much more holistic than secular legal systems: it also sets out the ethical rules that Muslims should aim to live and worship by. (A similar code governing both legal and ethical matters, halakha, exists in Judaism.) Sharia law is based on the Koran, Islam’s holy book; the hadith, or sayings of the prophet Mohammed; and the subsequent work of Islamic legal scholars. There are some very harsh punishments for crimes deemed against God (known as hudud), including death by stoning or 100 lashes for adulterers. But the standard of proof for conviction is extremely high, making these punishments rare. In the case of adultery, four witnesses must testify. Retribution for serious crimes against people, such as murder, can also be severe, based on the principle of qisas, or “an eye for an eye”. But Islam encourages victims to be merciful and pay diya, blood money, instead.

Sharia governs family law by defining the age of maturity and rules of marriage. Traditionally men are allowed up to four wives, though polygamy is rare in many Muslim countries today. In some, such as Tunisia, it has been banned. Adultery, sex before marriage, prostitution and sex between men are among acts termed zina, or unlawful. A religious marriage, or nikah, can often be dissolved unilaterally by the husband. Under most schools of sharia law women can also instigate divorce but must petition a court to do so. Perhaps the least familiar branch of sharia for Westerners is Islamic commercial law, which is built on the principles of fairness and certainty between contracted parties. Money lending is banned, as is insurance (though some funds based on shared risks are allowed), contracts that yield unclear returns, or any business that involves gambling, pork or alcohol (all of which are considered sinful). Islamic banks traditionally pay no interest, instead investing deposits and returning a cut of the profits (which amounts to much the same thing). In some Gulf states these rules have been relaxed, and investments and mortgages are governed by special contracts that limit risk. Banks often have a sharia board to ensure they comply.

Although parts of Sharia law are set out in the Koran, most of the system, like other legal frameworks, is flexible. Some countries make a show of imposing Islamic law strictly: in Kano state in Nigeria, Islamic police have banned shop mannequins with heads in case their lifelike forms provoke inappropriate thoughts. In other countries, such as Malaysia, the influence of sharia is more subtle. The harshest regimes, such as those imposed by Islamic State in Syria and Iraq, Al Shabab in Somalia and Afghanistan’s previous Taliban government, often stretch sharia’s dictates to their limits. The new Taliban government has promised moderation. Whether or not it means it will come down to its interpretation of sharia. Once the Taliban used it to justify banning photography. Now its fighters take selfies and post them online.

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