usul al-fiqh (the roots or sources of law)

Legal theory, the discipline of the study of the roots or sources of law, and of how to interpret them to arrive at legal rulings.

The sources of law:

The sources of law are traditionally listed as four:

• The Qur'an
• The Sunna
• Ijma` (consensus)
• Qiyas (analogy)

Of these, only the first two are revealed sources; the others are devices governing their interpretation.

Other sources that are acknowledged by different schools include:

• The sunna of the Companions of the Prophet and the following two generations of Muslims.
• The practice of the people of Medina.
• The laws of previous revelations.
• Public interest.
• The presumption that the basic lawfulness (or unlawfulness) of acts remains until it is explicitly changed by revelation.

The interpretation that a jurist performs in deriving an answer to a new legal question from the sources of law is called ijtihad (diligent inquiry).

How to interpret them:

The goal of usul al-fiqh is to determine which of the five legal values should be assigned to every human act. (The knowledge arrived at is called fiqh, the branches of law).

This requires analyzing the language of the Qur'an and Sunna to determine their meaning and resolve apparent contradictions, using concepts such as:

• Commands imply obligation unless evidence shows otherwise.
• Particular language always trumps general language.
• The meaning of a word may be definite, or only apparent, in which case evidence must be found to show which possible meaning is most apparent.
• Abrogation.

Other mechanisms provide answers to legal problems without reference to the meaning of the sources:

• Once a scholarly consensus is established, no new attempts to derive a legal value from the sources is permitted.
• One hadith may be favored over another because it has a more reliable isnad.
• If the sources do not yield a legal value, an analogy may be drawn to a similar legal problem.

In the traditionalist view, only an expert (a mufti, or issuer of legal opinions) is qualified to arrive at legal judgments, and others must follow his opinions, which may be right or wrong, but are always sufficient for gaining God's reward and avoiding punishment.