Several legal institutions in European civil law were adapted from similar institutions in Islamic law during the Middle Ages:
The Islamic Hawala institution influenced the development of the Avallo in Italian civil law and the Aval in French civil law.
The commenda limited partnership used in European civil law was also adapted from the Qirad and Mudaraba in Islamic law.
The civil law conception of res judicata and the transfer of debt, which was not permissible under Roman law but is practiced in modern civil law, may also have origins in Islamic law.
The concept of an agency was also an institution unknown to Roman law, where it was not possible for an individual to conclude a binding contract on behalf of another as his agent.
Islamic law also introduced two fundamental principles to the West, on which were to later stand the future structure of law: equity and good faith, which was a precursor to the concept of pacta sunt servanda in civil law and international law.
Another influence of Islamic law on the civil law tradition was the presumption of innocence, which was introduced to Europe by Louis IX of France soon after he returned from Palestine during the Crusades. Islamic law was based on the presumption of innocence from its beginning, as declared by Caliph Umar radhiallahu anhu in the 7th century.
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