Like all legal systems and theories, Islamic law and its legal theory are not free from ambiguity and tensions. Nowhere is such ambiguity more pronounced than in the treatment of ˓ada or custom (alternatively called ˓urf) in Islamic legal theory.
Generally, the term ˓ada is derived from Arabic, and means local customs, recurring habits, and social mores of the people. In the context of the epistemology of Islamic law, especially as it relates to what constitutes formal sources of law, classical Islamic jurisprudence does not recognize custom as a formal source. In the normative structure of Islamic law, it is the Qur˒ an as God's revealed word that is rated as the first primary source. Prophet Muhammad's sunna, that is, his conduct, authentic sayings, acts, and behavior that he approved is rated as the second primary source. In addition to these two sources there other sources (or legal principles) such as the consensus (ijma˒) of Muslim jurists or scholars and analogical reasoning (qiyas)—these combined then constitute what have become the normative formal sources of Islamic law.
However, notwithstanding the accepted normative hierarchy of what constitutes formal sources, Islam's encounter with other host cultures has compelled Islamic legal theory to evaluate the status of custom. For example, through such encounters, ˓ada, that is, the hitherto ambiguous source, has throughout the history of Islamic legal theory served as a flexible legal principle that helps Islamic law to evolve and thus meet the challenge of changing circumstances and times. This assertion finds ample support in Muslim juristic thinking. For example, a reflection on the founding jurists of the two main Sunni schools of Islamic law, namely, the Maliki and Hanafi schools, shows how various legal rules that were passed by the founders of these schools were based on the strength of communal practice and norms. A good example here is the ruling passed by Imam Malik b. Anas (d. 795 c.e.) that a woman cannot contract herself in marriage. On the same question, the Hanafi jurist, Imam Abu Hanifa (d. 767 c.e.) gave a different ruling that allowed a mature woman to contract herself. What is crucial to note here, though, is not so much the question of which of the two opinions is better, but rather the fact that the basis of the two legal rulings is primarily informed by social reality and what is popular communal practice. Noel James Coulson in his seminal article titled "Muslim Case Law" has presented a cogent argument in which he demonstrates that the opinion of Malik reflects the dominant view of marriage and the position of women within a predominantly patriarchal tribal society of Medina. And by contrast, Abu Hanifa's judgment mirrors the cosmopolitan nature of Kufa where women enjoyed a slightly more accommodating environment than in Medina.
Although often denied, the impact of ˓ada in Muslim legal theory is also evident in Muhammad b. Idris al-Shafi˓i (d. 819 c.e.), founder of the Shafi˓i school. For instance, the force of communal praxis and the ethos of Egypt obliged al-Shafi˓i to change a range of legal rulings that he sanctioned while in Baghdad before his migration to Egypt.
In addition to the aforementioned early jurists, the efficacy of ˓ada is also stressed by Abu Ishaq al-Shatibi (d. 1388) whom Wael Hallaq in his A History of Islamic Legal Theories regards as representing the "culmination" of maturity in Islamic legal theory. A critical reading of Shatibi's legal philosophy illustrates that ˓ada, though often measured under the concept of maslaha (public good), does occupy a central position in his legal thought. For Shatibi, Islamic law in its early phase, that is, in the prophetic era of Muhammad, simply confirmed most of the pre-Islamic Arabian customs practiced by the people before their acceptance of Islam. For example, Islamic laws like diya (blood money), rituals of hajj (pilgrimage), and interestingly even the Jum˓a (Muslim Friday congregational prayers), though taking a strict Islamic identity, were initially practices that were predominant in pre-Islamic Arabia. As habitual and popular customs these were rehabilitated by Islamic law and confirmed as Islamic practice.
Moving away from the formative classical period into the modern period, especially from the eighteenth to the twentieth century, examples gleaned from Africa and Asia also show that the predominance of custom not only shaped and influenced shari˓a, but custom became a law operating on its own right independent of shari˓a. What is discernible here is that custom in the modern context ceases to be merely a creative legal tool whose utility is only limited to make Islamic law adaptable to changing circumstances, but as "customary law" it becomes part of a dual legal system that is on par with shari˓a. Again, Coulson provides a good example when he points out how in both Africa and Asia local practices, especially as they pertain to land tenure, were mostly "regulated by customary rules" (p. 261). These either complemented shari˓a or simply subsumed it. For instance, in the Indian subcontinent this is illustrated in the popular "shari˓a act of 1937" that was initially designed to cater to all Muslims in the region. However, as it turned out, a majority of Muslims preferred to be exempted from shari˓a thus giving primacy to customary laws over the former.
Finally, it can be concluded that social exigencies, especially in the sociocommercial spheres, have compelled a majority of Muslim jurists, albeit reluctantly, to recognize ˓ada as a reliable legal tool. This recognition has come largely through what these jurists normally refer to as "creative legal devices." In particular, it is through these creative legal tools, of which custom is one of the central principles, that popular religious practices that would otherwise be rejected by shari˓a find acceptance. Thus maxims such as: "What is known through custom is legally binding" and "what is evident through custom is as authentic as the text or shari˓a" became acceptable principles in Islamic legal theory.
Hallaq, Wael. A History of Islamic Legal Theories: An Introduction to Sunni Usul al-Fiqh. Cambridge, U.K.: Cambridge University Press, 1993.
Kamali, Mohammad Hashim. Principles of Islamic Jurisprudence. Selangor, Malaysia: Pelanduk Publications, 1989.
Libson, Gideon. "On the Development of Custom as a Source of Law in Islamic Law." Islamic Law and Society 4, no. 2 (1997): 131–155.
Masud, Khalid M. Islamic Legal Philosophy: A Study of AbuIshaq al-Shatibi's Life and Thought. Delhi: International Publishers, 1989.
Ziadeh, Farhat. " Urf and Law in Islam." In The World ofIslam: Studies in Honor of Philip K. Hitti. Edited by J. Kritzek and R. Winder. London: Macmillan, 1959.
Tahir Fuzile Sitoto