One of the issues at the centre of the dispute between Henry II and the archbishop of Canterbury, Thomas Becket. The benefit released *clergy, 'criminous clerks', from the power of secular courts regarding various charges of felony and other offences, esp. when there was the possibility of the death penalty. This release could be claimed by the literate, proof of which was the ability to read the Scriptures. In time, though, men simply learned a text to recite by rote as proof. After Becket's death, benefit of clergy was conceded by the Church, apart from offences against forest law.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.