ثم إجماع من بعدهم فيما لم يوجد فيه قول السلف.
Then comes the consensus of later jurists on a matter in which no opinion of the predecessors had been reported.
A legal problem may arise for which no earlier specific view is recorded. Agreement by qualified jurists of a later period may then constitute this third form, provided it is genuinely established and not contradicted by a known earlier position.
It is still scholarly agreement, not a popular vote; the status of earlier disagreement must also be investigated.