What is the ruling on analyzing usury?

Usury is forbidden by the Qur'an, Sunnah, and the definitive consensus. Whoever deems it permissible disbelieves, because he has denied something upon which the scholars have reached a clear consensus. Belief in the prohibition of outwardly manifest and widely transmitted forbidden acts, such as fasting Ramadan and fornication, is among the fundamentals of faith, and whoever denies them is a disbeliever. However, if one denies the prohibition of a specific form of usury about which there was scholarly disagreement, or for which the consensus on its prohibition was not clear, then he does not disbelieve. Rather, his situation is examined, as he may be a mujtahid (one who exercises independent reasoning), excused, or a transgressor.