Islam in West Africa. As Islam spread in West Africa, Islamic principles of jurisprudence influenced changes to indigenous systems of law and justice in some parts of the region. At the heart of Islamic law (the shari'ah) is the belief in its divine origin. Muslims hold that the fundamental sources of all laws are the Quran (Koran) and the Sunnan (singular: Sunnah), customs and legal pronouncements of the Prophet Muhammad and other members of the early Muslim community. In making a ruling an Islamic judge also consults consensus interpretations made in earlier cases and draws analogies from established laws. Nonetheless, the judge understands the supremacy of the Quran—the will of God as revealed through Muhammad —above all other sources. Each of the two branches of Islam, Sunni and Shi'a, has four major schools of law. The dominant school...