Islam lays down rules governing all aspects of human behavior. These are known as the Sheria, which considered by muslims to be a Revealed code of Law that is eternal in place and time and to which to all human being are subject, and which provides for all the conduct needed for an orderly society.
Two fundamental concepts underlie Islamic morality; halal, which means permissible, and haram meaning forbidden. The basic principal is that nothing is haram except that which clearly prohibited by the Sheria.
The Sheria has two primary sources, the Quran and the Sunnah, and two secoundly sources, the Qiyas and the Ijma. The Quran is the word of God as revealed to prophet (PBUH). It was written down during his life and gathered together by His companions after his death. Sunnah refers to the actions and utterances of the prophet (PBUH) during his own life time, which, after his death, were written down and complied into various collections of Ahadith (saying). The Quran states the principles of the sheria while the sunnah provides examples of their application.
Qiyas is reasoning by analogy. It is applied where guidance from the Quran and the Sunnah is not directory available to answer an ethical query. Ijma is the consensus of Uiema (religious scholars). This consensus is applied where no clear conclusion based on the Quran or the Sunnah can be made on an ethical matter. Uiemas usually belong to colleges, whence from time to time they issue fatwas, ruling on particular matters that are considered binding.
Islamic jurisprudence of Fiqh consists of collections of law based on the Quran and the Sunnah. It is highly developed and there are several schools. The development of Fiqh is on-going, through a dialectic process known as Ijtehad; e.g., Islamic banking emerged as an alternative to conventional backing only within the last generation and is still evolving with many issues yet to be settled.
In an Islamic court all, including non-muslims, are equal before Sheria. A defendant is presumed innocent until proven guilty and the burden of proof falls on the complainant, who must produce witnesses, at least two and in some cases four, to prove his case. Witnesses must testify under oath and the testamentary value of a male witness is double that female.