In England especially, the definition of clergy was extended to include all who could read and write; see Ben Jonson.
The benefit of clergy had to be pled by a certain ritual, after conviction and before sentencing. The accused then had to read aloud a verse from the Bible; by tradition, the passage chosen was inevitably and appropriately Psalm 51, Miserere mei, Domine. (Have mercy upon me, O God.)1 As a result, this Psalm became known as the "neck verse;" knowing it could save your neck. Clergy could be pled but once; those who were convicted of a second felony were ineligible. Many crimes came to be defined by Parliament as "unclergyable;" in the words of the statutes, they were "felony without benefit of clergy."
In England, the benefit of clergy was declared unnecessary and thereby abolished in 1827. It had already been taken away by an Act of Congress in 1790 in the United States.