Max Weber has made popular his descriptions of the Islamic legal system in which he said decisions were arbitrary. According to Weber, only Western society due to its historical evolution has experienced a legal order based on a rational approach to law.

The Weberian perspectives on Islamic history and society, have been said among others to be based on predetermined paradigms and not on serious research.

What is perceived as arbitrary by the untrained mind is really the wealth of diversity of opinions of jurist-law arrived through ijtihad (independent reasoning). These opinions are not jurisprudentially speaking, arbitrary.

It might be more correct to say that some opinions may be less sound or less 'authoritative' on account of the methodology used. You may also end up with several sound opinions over a single issue.