The sources of Islamic jurisprudence are of two kinds. The first is drawn directly from the primary sources of the Qur’an and the Traditions. The other is secondary and includes ijma or unanimous agreement of jurists by analogy drawn from precedent. To this may be added the source of equity and custom which was the basis of the Hanafi and the Maliki schools. The study of these sources was the subject of a special science called Ilm Al-Usul. It gave rise to what is called ijtihad, i.e. the effort or endeavour to interpret legal sources and to discover proper solutions for religious and legal cases. Ijtihad was thus an important factor in Islamic legal history, in adapting rules to the need of civilisation, and was one of the causes of the florescence of Islamic jurisprudence in the Abbasside period. But after the fall of Baghdad in the 13th century, Islamic civilisation began to fade, and orthodox or Sunni jurists agreed that the four well-known Sunni schools, i.e. the Hanafi,Maliki, Shafi and Hanbali were sufficient. They thus agreed upon the closing of the door of ijtihad. As a result, new interpretations were prohibited, and consequently unconsidered and slavish imitation (taqlid) became general.1
The above four groups i.e. the Hanafi, Maliki, Shafi and Hanbali can be classed together as Ahle-fiqh. A later development of another Sunni group is the Ahle-hadith. The Shias similarly had developed into separate sects i.e. Kais’ania, Zaidia, Im’amia, Ism’ailia and, lastly, Ghali (now extinct).