Why people are hanged "until dead"

"A popular story in Edinburgh is that of Margaret Dickson, a fishwife from Musselburgh who was hanged in the Grassmarket in 1724 for murdering her illegitimate baby shortly after birth. After the hanging, her body was taken back to Musselburgh on a cart. However, on the way there she awoke. Since, under Scots Law, her punishment had been carried out, she could not be executed for a second time for the same crime (only later were the words "until dead" added to the sentence of hanging). Her "resurrection" was also to some extent seen as divine intervention, and so she was allowed to go free. In later life (and legend) she was referred to as "half-hangit Maggie". There is now a pub in the Grassmarket named after her."

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