Machine summary:
I contend that (1) the early jurists viewed this as the safest way to inoculate and safeguard that system (and the other sources) from individual abuse and personal manipulation and that (2) without consensus and why it was originally construed and framed (notwithstanding how it was applied) by the jurists, the Qur’an and the Sunnah (despite their inherent re- ligious and theological authority) would be meaningless or inadmissible as legitimate sources of law.
On matters related to general practice, all Muslims were deemed to participate in forming consensus, whereas on technical points of the law, the scholars had the monopoly.
Consensus makes sense if it is a source “through” which law is derived, because unlike the Qur’an and Sunnah it cannot be resorted to to locate the maxims and components with which to enact laws.
Jurists find the Qur’anic injunction, understand and analyze it, formulate the legal code, and then seek consensus to legitimize their under- standing, analysis, and enactment of the law.
I think credit should be given to the early Sunni scholars and, by exten- sion, to Islam for making consensus a source of the legal system.
Consensus, as a supporting source for the Qur’an and Sunnah, guarantees that no one can unilaterally enact laws based upon his own understanding.
Given this reality, it stands to reason that in the domain of law, consensus may be more crucial to support one’s understanding than one’s quotation of the Qur’an and Hadith.