No State can afford to ignore the customs of the land, not even conquerors that impose new legal systems on defeated countries.If it does, the people who follow these customs will revolt against the authority of the State.
By comparing decisions and by basing new decisions on preceding ones, they developed the Common Law. In our own times a judge, while applying the law, interprets it, and in doing so he modifies or explains it either subconsciously or deliberately.
Customs, too, are to be fitted to dynamic conditions of society and their rigidity is lubricated by the progressive social forces. This is done by judges, and Justice Holmes, of the United States Supreme Court, gave us a bare truth when he said that judges do and must make laws.
Islamic law now forms the basis of the legal system of the Islamic Republic of Pakistan replacing the prevailing laws by those ordained by the Quran and Shariat and evolving an Islamic Jurisprudence.
President Zia- ul-Haq, for instance, replaced the wealth tax and agriculture produce laws by Zakat and Usur.
Customs are not laws in the political sense of the term.
But when the State recognizes these customary rates as binding, they acquire the status of law.No one can say exactly when and how custom arose, “except that it was shaped by the cooperative action of the whole community and not by any kingly or legislative command.” But one thing is clear, that customs are accepted and followed as a matter of habit.Their sanction is utility or the general desire of men for order and justice. In the primitive society all disputes were decided in accordance with the prevailing social customs.In the beginning, when the social organisation was simple, customs were based on the general usage of the family, clan or tribe.In every country the greatest importance is attached by both judges and lawyers to the opinions of legal luminaries.The jurists collect and arrange in logical form past customs, decisions, and laws.Religion: In the primitive community custom was law and law was religion.Law and religion were so inextricably mixed up that the rules of life had a religious sanction.At that time the necessity was felt to supplement custom by interpretation.Whenever custom failed to give a just solution or was obviously not suited to the case, the dispute was decided according to commonsense. In the beginning they were oral and unwritten and passed from generation to generation by tradition.