The doctrine became a matter of state coercion rather than academic dispute in 833, when the caliph al-Mamun ordered provincial judges to administer a direct test: a scholar or judge seeking to give testimony or hold office had to affirm, under questioning, that the Quran was created. The mechanism came to be called the Mihna, the trial, and it ran under three successive caliphs, examining witnesses, imprisoning those who refused, and in a small number of cases flogging them, before the policy was abandoned around 848.
Ahmad ibn Hanbal's refusal under interrogation, and his imprisonment for it, is the case later Sunni memory fixed on, but he was neither the only nor the first scholar to hold out; what made his stand definitive was that he survived the Mihna and lived to see it reversed, so his position could be presented afterward not as one dissenting opinion among several but as the one events had vindicated. The reversal did not restore silence on the question. Later Ashari theology settled on a compromise the Mihna itself had made impossible to ignore, distinguishing the Quran's eternal, uncreated meaning from its created expression in sound and ink, a formula built specifically to hold both the tradition Ahmad had defended and the philosophical problem the Mutazila had originally raised.