In 18th-century England, the legal system was notorious for the 'Bloody Code,' which made over 200 offenses punishable by hanging. However, a remarkable loophole known as the 'Benefit of Clergy' provided an escape route for thousands of accused felons. Originating in the Middle Ages to protect ordained priests from secular courts, the privilege eventually expanded to anyone who could demonstrate literacy.
To prove one was educated enough to claim ecclesiastical immunity, judges required defendants to read aloud Psalm 51, Verse 1: 'Have mercy upon me, O God, according to thy lovingkindness.' This specific text became famously known as the 'Neck Verse' because reading it successfully saved the criminal's neck from the noose. Over time, actual literacy was no longer required; sympathetic jailers and lawyers coached completely illiterate defendants to memorize the Latin verse phonetically before trial.
Upon successfully reciting the lines, the defendant was branded on the thumb with an 'M' for malefactor or 'T' for tyburn to prevent them from claiming the benefit a second time, then set free.